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• 1. [Image] Seismicity Report on the Adak Island Project, Aleutian Islands, Alaska

  	In order to evaluate the geothermal potential of a project area on Adak Island, Aleutian Islands, Alaska, a high gain (40-750K), high frequency (5-30hz) microseismic network was operated for a period of ...
  	Citation × Citation Citation Abstract Copy Title: Seismicity Report on the Adak Island Project, Aleutian Islands, Alaska Author: Micro Geophysics Corporation Year: 1975 In order to evaluate the geothermal potential of a project area on Adak Island, Aleutian Islands, Alaska, a high gain (40-750K), high frequency (5-30hz) microseismic network was operated for a period of ten days in late October, 1974. The detection threshold determined from the recurrence curve was found to be below magnitude 0.0. Over 35 local events (S-P time less than four seconds) were detected, of which 26 events can be associated with a postulated fault in Andrew Bay near Mount Adagdak on the north side of Adak Island. First motion studies indicate that this fault is a right-lateral strike-slip fault with a small thrust component. Temporal and spatial variations of Poisson's Ratio within the interpreted fault zone (derived from velocity ratios and Wadati diagrams) have led to the derivation of a theoretical model of a dilatant region near Mount Adagdak. This region is interpreted as having the largest potential of the area surveyed for producing commercial earth steam Title: Seismicity Report on the Adak Island Project, Aleutian Islands, Alaska Author: Micro Geophysics Corporation Year: 1975 In order to evaluate the geothermal potential of a project area on Adak Island, Aleutian Islands, Alaska, a high gain (40-750K), high frequency (5-30hz) microseismic network was operated for a period of ten days in late October, 1974. The detection threshold determined from the recurrence curve was found to be below magnitude 0.0. Over 35 local events (S-P time less than four seconds) were detected, of which 26 events can be associated with a postulated fault in Andrew Bay near Mount Adagdak on the north side of Adak Island. First motion studies indicate that this fault is a right-lateral strike-slip fault with a small thrust component. Temporal and spatial variations of Poisson's Ratio within the interpreted fault zone (derived from velocity ratios and Wadati diagrams) have led to the derivation of a theoretical model of a dilatant region near Mount Adagdak. This region is interpreted as having the largest potential of the area surveyed for producing commercial earth steam Close

• 2. [Image] Volcano and earthquake hazards in the Crater Lake Region, Oregon: open file report 97-487

  	ill., maps; Folded map in back cover; Includes bibliographical references ( p. 27-30) and glossary; Report accompanied by: Volcano hazard zones, volcanic vents, faults in the Crater Lake Region, Oregon ...
  	Citation × Citation Citation Abstract Copy Title: Volcano and earthquake hazards in the Crater Lake Region, Oregon: open file report 97-487 Author: Bacon, Charles R. Year: 1997, 2008 ill., maps; Folded map in back cover; Includes bibliographical references ( p. 27-30) and glossary; Report accompanied by: Volcano hazard zones, volcanic vents, faults in the Crater Lake Region, Oregon [map] Title: Volcano and earthquake hazards in the Crater Lake Region, Oregon: open file report 97-487 Author: Bacon, Charles R. Year: 1997, 2008 ill., maps; Folded map in back cover; Includes bibliographical references ( p. 27-30) and glossary; Report accompanied by: Volcano hazard zones, volcanic vents, faults in the Crater Lake Region, Oregon [map] Close

• 3. [Image] Cascadia : a quarterly publication of the Oregon Department of Geology & Mineral Industries, volume 2, number 1 (Winter/Spring 2002)

  	Water and geology: how does geology control where you find and how you use water? / Roddey, James -- Through the eyes of the state geologist / Beaulieu, John D. -- What is groundwater? -- Geology and groundwater ...
  	Citation × Citation Citation Abstract Copy Title: Cascadia : a quarterly publication of the Oregon Department of Geology & Mineral Industries, volume 2, number 1 (Winter/Spring 2002) Author: Oregon. Dept. of Geology and Mineral Industries Year: 2002, 2005 Water and geology: how does geology control where you find and how you use water? / Roddey, James -- Through the eyes of the state geologist / Beaulieu, John D. -- What is groundwater? -- Geology and groundwater -- Who owns and manages Oregon's water? -- Recent geologic efforts related to groundwater -- A groundwater case study: Catherine Creek and the Upper Grande Ronde Valley -- McKenzie - Willamette River confluence project Title: Cascadia : a quarterly publication of the Oregon Department of Geology & Mineral Industries, volume 2, number 1 (Winter/Spring 2002) Author: Oregon. Dept. of Geology and Mineral Industries Year: 2002, 2005 Water and geology: how does geology control where you find and how you use water? / Roddey, James -- Through the eyes of the state geologist / Beaulieu, John D. -- What is groundwater? -- Geology and groundwater -- Who owns and manages Oregon's water? -- Recent geologic efforts related to groundwater -- A groundwater case study: Catherine Creek and the Upper Grande Ronde Valley -- McKenzie - Willamette River confluence project Close

• 4. [Image] Oregon Plan for Salmon and Watersheds biennial report, 2005-2007

  	The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing ...
  	Citation × Citation Citation Abstract Copy Title: Oregon Plan for Salmon and Watersheds biennial report, 2005-2007 Author: Oregon Watershed Enhancement Board Year: 2006, 2007 The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing efforts of people throughout Oregon to improve and protect clean water and recover and maintain healthy populations offish and wildlife in our watersheds. The Oregon Plan is unique because it engages communities in the restoration and long-term stewardship of their watersheds. This extraordinary effort encourages local partnerships and voluntary actions to improve the conditions of our watersheds. Over the years, these actions have made Oregon a national leader in local cooperative conservation. This report collects project and condition data, voluntary private lands restoration information, and agency program accomplishments under the Oregon Plan. Consistent with the past two reports, this document continues to provide specific data on each of the state's fifteen reporting basins. A new element to this report is the inclusion of stories about the people, partnerships, and on-the-ground projects that are benefiting watersheds and communities across the state. Thanks to the many Oregon Plan partners who contributed to this report. Thomas M. Byler Executive Director Oregon Watershed Enhancement Board Title: Oregon Plan for Salmon and Watersheds biennial report, 2005-2007 Author: Oregon Watershed Enhancement Board Year: 2006, 2007 The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing efforts of people throughout Oregon to improve and protect clean water and recover and maintain healthy populations offish and wildlife in our watersheds. The Oregon Plan is unique because it engages communities in the restoration and long-term stewardship of their watersheds. This extraordinary effort encourages local partnerships and voluntary actions to improve the conditions of our watersheds. Over the years, these actions have made Oregon a national leader in local cooperative conservation. This report collects project and condition data, voluntary private lands restoration information, and agency program accomplishments under the Oregon Plan. Consistent with the past two reports, this document continues to provide specific data on each of the state's fifteen reporting basins. A new element to this report is the inclusion of stories about the people, partnerships, and on-the-ground projects that are benefiting watersheds and communities across the state. Thanks to the many Oregon Plan partners who contributed to this report. Thomas M. Byler Executive Director Oregon Watershed Enhancement Board Close

• 5. [Article] Melting in the Mantle Wedge: Quantifying the Effects of Crustal Morphology and Viscous Decoupling on Melt Production with Application to the Cascadia Subduction Zone

  Arc magmatism is sustained by the complex interactions between the subducting slab, the overriding plate, and the mantle wedge. Partial melting of mantle peridotite is achieved by fluid-induced flux melting ...

  Citation × Citation Citation Abstract Copy Title: Melting in the Mantle Wedge: Quantifying the Effects of Crustal Morphology and Viscous Decoupling on Melt Production with Application to the Cascadia Subduction Zone Author: Yang, Jiaming Year: 2017 Arc magmatism is sustained by the complex interactions between the subducting slab, the overriding plate, and the mantle wedge. Partial melting of mantle peridotite is achieved by fluid-induced flux melting and decompression melting due to upward flow. The distribution of melting is sensitive to temperature, the pattern of flow, and the pressure in the mantle wedge. The arc front is the surface manifestation of partial melting in the mantle wedge and is characterized by a narrow chain of active volcanoes that migrate in time. The conventional interpretation is that changes in slab dip angle lead to changes in the arc front position relative to the trench. We explore an alternative hypothesis: evolution of the overlying plate, specifically thickening of the arc root, causes arc front migration. We investigate the effects of varying crustal morphology and viscous decoupling of the shallow slab-mantle interface on melt production using 2D numerical models involving a stationary overriding plate, a subducting plate with prescribed motion, and a dynamic mantle wedge. Melt production is quantified using a hydrous melting parameterization. We conclude: 1) Localized lithospheric thickening shifts the locus of melt production trenchward while thinning shifts melting landward. 2) Inclined LAB topography modulates the asthenospheric flow field, producing a narrow, well-defined arc front. 3) Thickening of the overriding plate exerts increased torque on the slab, favoring shallowing of the dip angle. 4) Viscous decoupling produces a cold, stagnant forearc mantle but promotes arc front melting due to reduction in the radius of corner flow, leading to higher temperatures at the coupling/decoupling transition. Title: Melting in the Mantle Wedge: Quantifying the Effects of Crustal Morphology and Viscous Decoupling on Melt Production with Application to the Cascadia Subduction Zone Author: Yang, Jiaming Year: 2017 Arc magmatism is sustained by the complex interactions between the subducting slab, the overriding plate, and the mantle wedge. Partial melting of mantle peridotite is achieved by fluid-induced flux melting and decompression melting due to upward flow. The distribution of melting is sensitive to temperature, the pattern of flow, and the pressure in the mantle wedge. The arc front is the surface manifestation of partial melting in the mantle wedge and is characterized by a narrow chain of active volcanoes that migrate in time. The conventional interpretation is that changes in slab dip angle lead to changes in the arc front position relative to the trench. We explore an alternative hypothesis: evolution of the overlying plate, specifically thickening of the arc root, causes arc front migration. We investigate the effects of varying crustal morphology and viscous decoupling of the shallow slab-mantle interface on melt production using 2D numerical models involving a stationary overriding plate, a subducting plate with prescribed motion, and a dynamic mantle wedge. Melt production is quantified using a hydrous melting parameterization. We conclude: 1) Localized lithospheric thickening shifts the locus of melt production trenchward while thinning shifts melting landward. 2) Inclined LAB topography modulates the asthenospheric flow field, producing a narrow, well-defined arc front. 3) Thickening of the overriding plate exerts increased torque on the slab, favoring shallowing of the dip angle. 4) Viscous decoupling produces a cold, stagnant forearc mantle but promotes arc front melting due to reduction in the radius of corner flow, leading to higher temperatures at the coupling/decoupling transition. Close

• 6. [Article] Links from Mantle to Microbe at the Lau Integrated Study Site: Insights from a Back-Arc Spreading Center

  The Lau Integrated Study Site (ISS) has provided unique opportunities for study of ridge processes because of its back-arc setting in the southwestern Pacific. Its location allows study of a biogeographical ...

  Citation × Citation Citation Abstract Copy Title: Links from Mantle to Microbe at the Lau Integrated Study Site: Insights from a Back-Arc Spreading Center Author: Tivey, Margaret K., Becker, Erin, Beinart, Roxanne, Fisher, Charles R., Girguis, Peter, Langmuir, Charles H., Michael, Peter J., Reysenbach, Anna-Louise Year: 2012 The Lau Integrated Study Site (ISS) has provided unique opportunities for study of ridge processes because of its back-arc setting in the southwestern Pacific. Its location allows study of a biogeographical province distinct from those of eastern Pacific and mid-Atlantic ridges, and crustal compositions along the ridge lie outside the range of mid-ocean ridge crustal compositions. The Lau ISS is located above a subduction zone, at an oblique angle. The underlying mantle receives water and other elements derived from the downgoing lithospheric slab, with an increase in slab influence from north to south. Water lowers the mantle melting temperature and leads to greater melt production where the water flux is greater, and to distinctive regional-scale gradients along the ridge. There are deeper faulted axial valleys with basaltic volcanism in the north and inflated axial highs with andesites in the south. Differences in igneous rock composition and release of magmatic volatiles affect compositions of vent fluids and deposits. Differences in vent fluid compositions and small-scale diffuse-flow regimes correlate with regional-scale patterns in microbial and megafaunal distributions. The interdisciplinary research effort at the Lau ISS has successfully identified linkages between subsurface processes and deep-sea biological communities, from mantle to microbe to megafauna. Title: Links from Mantle to Microbe at the Lau Integrated Study Site: Insights from a Back-Arc Spreading Center Author: Tivey, Margaret K., Becker, Erin, Beinart, Roxanne, Fisher, Charles R., Girguis, Peter, Langmuir, Charles H., Michael, Peter J., Reysenbach, Anna-Louise Year: 2012 The Lau Integrated Study Site (ISS) has provided unique opportunities for study of ridge processes because of its back-arc setting in the southwestern Pacific. Its location allows study of a biogeographical province distinct from those of eastern Pacific and mid-Atlantic ridges, and crustal compositions along the ridge lie outside the range of mid-ocean ridge crustal compositions. The Lau ISS is located above a subduction zone, at an oblique angle. The underlying mantle receives water and other elements derived from the downgoing lithospheric slab, with an increase in slab influence from north to south. Water lowers the mantle melting temperature and leads to greater melt production where the water flux is greater, and to distinctive regional-scale gradients along the ridge. There are deeper faulted axial valleys with basaltic volcanism in the north and inflated axial highs with andesites in the south. Differences in igneous rock composition and release of magmatic volatiles affect compositions of vent fluids and deposits. Differences in vent fluid compositions and small-scale diffuse-flow regimes correlate with regional-scale patterns in microbial and megafaunal distributions. The interdisciplinary research effort at the Lau ISS has successfully identified linkages between subsurface processes and deep-sea biological communities, from mantle to microbe to megafauna. Close

• 7. [Article] Seismic Hazard Assessment of Oregon Highway Truck Routes

  This research project developed a seismic risk assessment model along the major truck routes in Oregon. The study had adopted federally developed software tools called Risk for Earthquake Damage to Roadway ...

  Citation × Citation Citation Abstract Copy Title: Seismic Hazard Assessment of Oregon Highway Truck Routes Author: Dusicka, Peter, Mehary, Selamawit Tesfayesus Year: 2012 This research project developed a seismic risk assessment model along the major truck routes in Oregon. The study had adopted federally developed software tools called Risk for Earthquake Damage to Roadway Systems (REDARS2) and HAZUS-MH. The model was the first time REDARS2 has been adopted and used in research outside of the original development team, presenting a number of unique challenges. The development of the model was a complex, intensive process that required a significant research effort, manipulation and adjustment of data. Furthermore, limitations of the software tools themselves had been identified that prevented the inclusion of important aspects such as liquefaction induced damage and refinement of the transportation network. The main objective of this research were to refine the data from a first generation of the model to more realistically represent the bridge inventory, to address the seismicity of the Pacific Northwest, conduct sensitivity analyses of soil data on the analyses results and develop a seismic network model of Oregon bridges for purposes of assessing the seismic vulnerability of roadway segments. The first generation model relied on default settings within the program to determine the economic loss due to repair and replacement of damaged bridges. The assumptions used in the analyses have been reviewed and Oregon specific data was incorporated for the model. The largest earthquake now considered to be at a highest level of probability in the Pacific Northwest is a subduction zone earthquake. The major shortcoming of REDARS2 is its inability to incorporate the subduction zone attenuation relationship into the analysis. To incorporate that capability into the model, shakemaps were developed by USGS for Cascadia subduction zone scenario events and incorporated as the demand on the refined model. Analyses of the transportation network incorporating bridge routes and post processing of the data with input from Oregon DOT bridge engineers resulted in recommendations toward bridge route priority strategies. The majority of the bridges that indicated the possibility of damage were types associated with multi-column bents, simply-supported concrete superstructures and simply-supported steel superstructures. Of the major highway routes that were considered, I-405, section of I-5 (from Multnomah to Clackamas Counties), I-84, I-205 and US-101 were the top five on the preliminary priority for seismic retrofit. These routes need to be analyzed more and advanced cost-benefit investigations should be done before retrofit decisions are made. Title: Seismic Hazard Assessment of Oregon Highway Truck Routes Author: Dusicka, Peter, Mehary, Selamawit Tesfayesus Year: 2012 This research project developed a seismic risk assessment model along the major truck routes in Oregon. The study had adopted federally developed software tools called Risk for Earthquake Damage to Roadway Systems (REDARS2) and HAZUS-MH. The model was the first time REDARS2 has been adopted and used in research outside of the original development team, presenting a number of unique challenges. The development of the model was a complex, intensive process that required a significant research effort, manipulation and adjustment of data. Furthermore, limitations of the software tools themselves had been identified that prevented the inclusion of important aspects such as liquefaction induced damage and refinement of the transportation network. The main objective of this research were to refine the data from a first generation of the model to more realistically represent the bridge inventory, to address the seismicity of the Pacific Northwest, conduct sensitivity analyses of soil data on the analyses results and develop a seismic network model of Oregon bridges for purposes of assessing the seismic vulnerability of roadway segments. The first generation model relied on default settings within the program to determine the economic loss due to repair and replacement of damaged bridges. The assumptions used in the analyses have been reviewed and Oregon specific data was incorporated for the model. The largest earthquake now considered to be at a highest level of probability in the Pacific Northwest is a subduction zone earthquake. The major shortcoming of REDARS2 is its inability to incorporate the subduction zone attenuation relationship into the analysis. To incorporate that capability into the model, shakemaps were developed by USGS for Cascadia subduction zone scenario events and incorporated as the demand on the refined model. Analyses of the transportation network incorporating bridge routes and post processing of the data with input from Oregon DOT bridge engineers resulted in recommendations toward bridge route priority strategies. The majority of the bridges that indicated the possibility of damage were types associated with multi-column bents, simply-supported concrete superstructures and simply-supported steel superstructures. Of the major highway routes that were considered, I-405, section of I-5 (from Multnomah to Clackamas Counties), I-84, I-205 and US-101 were the top five on the preliminary priority for seismic retrofit. These routes need to be analyzed more and advanced cost-benefit investigations should be done before retrofit decisions are made. Close

• 8. [Article] Reducing Seismic Risk to Highway Mobility: Assessment and Design Examples for Pile Foundations Affected by Lateral Spreading

  Damage in pile supported structures due to liquefaction and liquefaction induced deformation were reported in past earthquakes around the world (e.g., Ansal et al. 1999; Seed et al. 1990; EERI 2010, EERI ...

  Citation × Citation Citation Abstract Copy Title: Reducing Seismic Risk to Highway Mobility: Assessment and Design Examples for Pile Foundations Affected by Lateral Spreading Author: Ashford, Scott A., Scott, Michael H., Rayamajhi, Deepak Year: 2013 Damage in pile supported structures due to liquefaction and liquefaction induced deformation were reported in past earthquakes around the world (e.g., Ansal et al. 1999; Seed et al. 1990; EERI 2010, EERI 2011; GEER 2010a, GEER 2010b, GEER 2011). For example, a reconnaissance report from a recent subduction zone event, the 2010 Chile earthquake (Mw=8.8), showed the pervasive nature of liquefaction and liquefaction-induced lateral spreading damage to bridge foundations (GEER 2010a, Yen et al. 2011). In terms of seismic hazard, the Pacific Northwest shares similar conditions from a Cascadia Subduction Zone (CSZ) earthquake source with the expected earthquake magnitude of 9.0 (Mw) and return period of 300 years (Atwater et al. 1995, Atwater and Hemphill-Halley 1997). The risk and damage from a CSZ earthquake event is widely recognized by the Oregon Department of Transportation (ODOT) as presented in a report by ODOT (2009). A large number of bridges were found to be vulnerable to a CSZ event, and repair and replacement costs of Oregon bridges have been estimated at more than 1 billion USD (ODOT 2009). Moreover, thousands of bridges require some kind of modification and/or seismic retrofitting to the foundation in order to improve seismic performance under liquefaction induced lateral spreading. To evaluate the seismic performance of bridge foundations and liquefaction mitigation alternatives, ODOT/OTREC funded collaborative research between Oregon State University (OSU), University of California at Davis (UCD), University of California at San Diego (UCSD), Hayward Baker Inc., and Pacific Earthquake Engineering Research Center (PEER). The main objectives of the research were to develop design charts for different liquefaction mitigation alternatives and to develop methodologies for assessing the performance of bridge pile foundations in laterally spreading ground. The cooperative research focuses on two aspects of liquefaction and liquefaction induced lateral spreading: (1) ground improvement methods, particularly using stone columns and deep soil mixing (DSM) grids, and (2) assess the seismic performance of bridge foundations (e.g., drilled shaft, pile groups) and seismic retrofitting alternatives for the bridge foundation. Stone columns for liquefaction mitigation and pile groups foundation assessment were investigated by the OSU team, while DSM and large diameter piles/shafts alternatives were investigated by the UCD team. Research teams used OpenSees (http://opensees.berkeley.edu/), an open source computational platform for three dimensional (3D) finite element (FE) modeling and analysis. OpenSeesPL, a graphical user interface developed by the UCSD team, was used to investigate liquefaction mitigation alternatives (i.e., stone columns and DSM grids) and the performance of pile foundations in liquefaction induced laterally spreading ground. Title: Reducing Seismic Risk to Highway Mobility: Assessment and Design Examples for Pile Foundations Affected by Lateral Spreading Author: Ashford, Scott A., Scott, Michael H., Rayamajhi, Deepak Year: 2013 Damage in pile supported structures due to liquefaction and liquefaction induced deformation were reported in past earthquakes around the world (e.g., Ansal et al. 1999; Seed et al. 1990; EERI 2010, EERI 2011; GEER 2010a, GEER 2010b, GEER 2011). For example, a reconnaissance report from a recent subduction zone event, the 2010 Chile earthquake (Mw=8.8), showed the pervasive nature of liquefaction and liquefaction-induced lateral spreading damage to bridge foundations (GEER 2010a, Yen et al. 2011). In terms of seismic hazard, the Pacific Northwest shares similar conditions from a Cascadia Subduction Zone (CSZ) earthquake source with the expected earthquake magnitude of 9.0 (Mw) and return period of 300 years (Atwater et al. 1995, Atwater and Hemphill-Halley 1997). The risk and damage from a CSZ earthquake event is widely recognized by the Oregon Department of Transportation (ODOT) as presented in a report by ODOT (2009). A large number of bridges were found to be vulnerable to a CSZ event, and repair and replacement costs of Oregon bridges have been estimated at more than 1 billion USD (ODOT 2009). Moreover, thousands of bridges require some kind of modification and/or seismic retrofitting to the foundation in order to improve seismic performance under liquefaction induced lateral spreading. To evaluate the seismic performance of bridge foundations and liquefaction mitigation alternatives, ODOT/OTREC funded collaborative research between Oregon State University (OSU), University of California at Davis (UCD), University of California at San Diego (UCSD), Hayward Baker Inc., and Pacific Earthquake Engineering Research Center (PEER). The main objectives of the research were to develop design charts for different liquefaction mitigation alternatives and to develop methodologies for assessing the performance of bridge pile foundations in laterally spreading ground. The cooperative research focuses on two aspects of liquefaction and liquefaction induced lateral spreading: (1) ground improvement methods, particularly using stone columns and deep soil mixing (DSM) grids, and (2) assess the seismic performance of bridge foundations (e.g., drilled shaft, pile groups) and seismic retrofitting alternatives for the bridge foundation. Stone columns for liquefaction mitigation and pile groups foundation assessment were investigated by the OSU team, while DSM and large diameter piles/shafts alternatives were investigated by the UCD team. Research teams used OpenSees (http://opensees.berkeley.edu/), an open source computational platform for three dimensional (3D) finite element (FE) modeling and analysis. OpenSeesPL, a graphical user interface developed by the UCSD team, was used to investigate liquefaction mitigation alternatives (i.e., stone columns and DSM grids) and the performance of pile foundations in liquefaction induced laterally spreading ground. Close

• 9. [Article] Seismic Retrofit Benefit Considering Statewide Transportation Assessment

  The purpose of this study was to identify and demonstrate a methodology to prioritize bridges for retrofit in the State of Oregon. Given the limited resources available, retrofitting all vulnerable bridges ...

  Citation × Citation Citation Abstract Copy Title: Seismic Retrofit Benefit Considering Statewide Transportation Assessment Author: Mehary, Selamawit Tesfayesus, Dusicka, Peter Year: 2015 The purpose of this study was to identify and demonstrate a methodology to prioritize bridges for retrofit in the State of Oregon. Given the limited resources available, retrofitting all vulnerable bridges in the foreseeable future would not be practical. Instead, a retrofit strategy needs to be developed to prioritize the inventory and enumerate the retrofit cost. In this study, a prioritization methodology used a holistic assessment of overall roadway system to consider highway route segments, rather than individual bridges. The overall assessment was based on a cost-benefit analysis including retrofit cost, expected economic loss (with or without retrofit) and social loss caused by system wide travel time delays. A review of 2010 ODOT bridge inventory suggested that a continuous concrete girder bridge (CCGS) with three spans could be utilized to represent a sizeable portion of vulnerable inventory for Oregon highways bridges. After reviewing several potential retrofit measures, carbon fiber composite material was selected for retrofit of vulnerable columns representing those built from the 1950s to mid-1970s. Four full-scale typical square columns were tested to failure. The results showed that despite the intentionally selected square geometry of the reinforced concrete columns, the CFRP composite material showed to be an effective retrofit measure and could be deployed for to address this deficiency. The software package REDARS2 was used for seismic risk analysis (SRA) of the highway network in this study. This platform was adopted to simulate the impact of scenario earthquakes in an effort to assess the expected benefit considering direct bridge costs as well as social costs from traffic induced delays resulting from seismic retrofitting of a particular bridge type. The assessment considered three scenario Cascadia Subsection Zone earthquakes of magnitudes 9.0, 8.5 North, and, 8.5 South. The study area included all highway routes west of the I-5 corridor, highway routes in the Portland area, the entire length of US-101 and extending partially east on I-84 Columbia River Highway. Due to the considerations of a single bridge type and other limitations identified in the seismic analysis software (REDARS2), the retrofit assessment outcomes should be regarded as a first order estimate. Title: Seismic Retrofit Benefit Considering Statewide Transportation Assessment Author: Mehary, Selamawit Tesfayesus, Dusicka, Peter Year: 2015 The purpose of this study was to identify and demonstrate a methodology to prioritize bridges for retrofit in the State of Oregon. Given the limited resources available, retrofitting all vulnerable bridges in the foreseeable future would not be practical. Instead, a retrofit strategy needs to be developed to prioritize the inventory and enumerate the retrofit cost. In this study, a prioritization methodology used a holistic assessment of overall roadway system to consider highway route segments, rather than individual bridges. The overall assessment was based on a cost-benefit analysis including retrofit cost, expected economic loss (with or without retrofit) and social loss caused by system wide travel time delays. A review of 2010 ODOT bridge inventory suggested that a continuous concrete girder bridge (CCGS) with three spans could be utilized to represent a sizeable portion of vulnerable inventory for Oregon highways bridges. After reviewing several potential retrofit measures, carbon fiber composite material was selected for retrofit of vulnerable columns representing those built from the 1950s to mid-1970s. Four full-scale typical square columns were tested to failure. The results showed that despite the intentionally selected square geometry of the reinforced concrete columns, the CFRP composite material showed to be an effective retrofit measure and could be deployed for to address this deficiency. The software package REDARS2 was used for seismic risk analysis (SRA) of the highway network in this study. This platform was adopted to simulate the impact of scenario earthquakes in an effort to assess the expected benefit considering direct bridge costs as well as social costs from traffic induced delays resulting from seismic retrofitting of a particular bridge type. The assessment considered three scenario Cascadia Subsection Zone earthquakes of magnitudes 9.0, 8.5 North, and, 8.5 South. The study area included all highway routes west of the I-5 corridor, highway routes in the Portland area, the entire length of US-101 and extending partially east on I-84 Columbia River Highway. Due to the considerations of a single bridge type and other limitations identified in the seismic analysis software (REDARS2), the retrofit assessment outcomes should be regarded as a first order estimate. Close

• 10. [Article] Research Project Work Plan for Impact of Cascadia Subduction Zone Earthquake on the Seismic Evaluation Criteria of Bridges

  The goal of this project is to provide ODOT with the best rational estimate of ground acceleration values for designing new and retrofitting existing bridges. The objectives are to: evaluate the hazard ...

  Citation × Citation Citation Abstract Copy Title: Research Project Work Plan for Impact of Cascadia Subduction Zone Earthquake on the Seismic Evaluation Criteria of Bridges Author: Dusicka, Peter Year: 2013 The goal of this project is to provide ODOT with the best rational estimate of ground acceleration values for designing new and retrofitting existing bridges. The objectives are to: evaluate the hazard by contrasting the acceleration values from individual CSZ events to PSHA values provide experimental evidence of damage difference under longer duration shaking expected from CSZ event Title: Research Project Work Plan for Impact of Cascadia Subduction Zone Earthquake on the Seismic Evaluation Criteria of Bridges Author: Dusicka, Peter Year: 2013 The goal of this project is to provide ODOT with the best rational estimate of ground acceleration values for designing new and retrofitting existing bridges. The objectives are to: evaluate the hazard by contrasting the acceleration values from individual CSZ events to PSHA values provide experimental evidence of damage difference under longer duration shaking expected from CSZ event Close

• 11. [Article] Mapped Overland Distance of Paleotsunami High-Velocity Inundation n Back-Barrier Wetlands of the Central Cascadia Margin, U.S.A

  Investigations of back-barrier, open-coastal plain settings have been used to establish minimum inundation distances of prehistoric tsunamis produced by great subduction zone earthquakes in the central ...

  Citation × Citation Citation Abstract Copy Title: Mapped Overland Distance of Paleotsunami High-Velocity Inundation n Back-Barrier Wetlands of the Central Cascadia Margin, U.S.A Author: Schlichting, Robert B., Peterson, Curt D. Year: 2006 Investigations of back-barrier, open-coastal plain settings have been used to establish minimum inundation distances of prehistoric tsunamis produced by great subduction zone earthquakes in the central Cascadia margin. Distinctive sand sheets were characterized at four localities within the central Cascadia margin, a shoreline distance of about 250 km. The sand sheets vary in thickness from 0.2 to 25 cm. They thin in the landward direction and consist of well-sorted beach sand that fines upsection. Many of the sand sheets include capping layers of organic-rich detritus, as well as assimilated mud rip-up clasts and soil litter. Marine diatoms and bromine (i.e., marine tracers) were used to confirm marine surge origins for the anomalous sand sheets. Radiocarbon dating of the sand sheets demonstrates correspondence with reported great Cascadia earthquake events at 0.3, ~1.1, ~1.3, ~1.7, and ~2.5 Ka. One sand sheet mapped at all four localities is dated at 600-950 calibrated radiocarbon years before present. This interpreted paleotsunami event does not correspond to a central Cascadia rupture, so it is tentatively assigned to a far-field source. Minimum overland inundation distances of the near field (Cascadia tsunami) at the four study localities range from 0.3 to 1.3 km, with a mean inundation for all sand sheets of 0.5 km. Title: Mapped Overland Distance of Paleotsunami High-Velocity Inundation n Back-Barrier Wetlands of the Central Cascadia Margin, U.S.A Author: Schlichting, Robert B., Peterson, Curt D. Year: 2006 Investigations of back-barrier, open-coastal plain settings have been used to establish minimum inundation distances of prehistoric tsunamis produced by great subduction zone earthquakes in the central Cascadia margin. Distinctive sand sheets were characterized at four localities within the central Cascadia margin, a shoreline distance of about 250 km. The sand sheets vary in thickness from 0.2 to 25 cm. They thin in the landward direction and consist of well-sorted beach sand that fines upsection. Many of the sand sheets include capping layers of organic-rich detritus, as well as assimilated mud rip-up clasts and soil litter. Marine diatoms and bromine (i.e., marine tracers) were used to confirm marine surge origins for the anomalous sand sheets. Radiocarbon dating of the sand sheets demonstrates correspondence with reported great Cascadia earthquake events at 0.3, ~1.1, ~1.3, ~1.7, and ~2.5 Ka. One sand sheet mapped at all four localities is dated at 600-950 calibrated radiocarbon years before present. This interpreted paleotsunami event does not correspond to a central Cascadia rupture, so it is tentatively assigned to a far-field source. Minimum overland inundation distances of the near field (Cascadia tsunami) at the four study localities range from 0.3 to 1.3 km, with a mean inundation for all sand sheets of 0.5 km. Close

• 12. [Article] Late Holocene Tsunami Deposits at Salt Creek, Washington, USA

  We interpret two thin sand layers in the estuarine marsh at Salt Creek, on the southern shore of the Strait of Juan de Fuca, as the products of tsunamis propagated by earthquakes at the Cascadia subduction ...

  Citation × Citation Citation Abstract Copy Title: Late Holocene Tsunami Deposits at Salt Creek, Washington, USA Author: Hutchinson, Ian, Peterson, Curt D., Sterling, Sarah L. Year: 2013 We interpret two thin sand layers in the estuarine marsh at Salt Creek, on the southern shore of the Strait of Juan de Fuca, as the products of tsunamis propagated by earthquakes at the Cascadia subduction zone. The sand layers extend for about 60 m along the left bank of the creek about 800 m from the mouth, and can be traced to the base of a nearby upland area. One layer is exposed in the creek bank about 400 m further upstream, but they are only patchily distributed in the rest of the central area of the marsh. Both layers contain brackish-marine epipsammic diatoms. The lower sand layer marks a sharp contact between intertidal peaty mud and overlying mud, perhaps reflecting modest coseismic subsidence in association with tsunami deposition, but little or no change in the bracketing sediment occurs in association with the upper sand layer. The ages of the sand layers are not closely constrained, but were most likely deposited by tsunamis generated by great earthquakes at the Cascadia subduction zone about 1650 and 1300 years ago. The Cascadia great earthquake of AD1700 may have induced slight subsidence in the marsh, but no tsunami deposit was detected at the inferred contact. The absence of deposits from the marsh immediately inland of the 4 m-high barrier beach indicates that the largest tsunamis in the late Holocene at this site have not overtopped the barrier, which suggests that these tsunamis were likely only 2-3 m high. Title: Late Holocene Tsunami Deposits at Salt Creek, Washington, USA Author: Hutchinson, Ian, Peterson, Curt D., Sterling, Sarah L. Year: 2013 We interpret two thin sand layers in the estuarine marsh at Salt Creek, on the southern shore of the Strait of Juan de Fuca, as the products of tsunamis propagated by earthquakes at the Cascadia subduction zone. The sand layers extend for about 60 m along the left bank of the creek about 800 m from the mouth, and can be traced to the base of a nearby upland area. One layer is exposed in the creek bank about 400 m further upstream, but they are only patchily distributed in the rest of the central area of the marsh. Both layers contain brackish-marine epipsammic diatoms. The lower sand layer marks a sharp contact between intertidal peaty mud and overlying mud, perhaps reflecting modest coseismic subsidence in association with tsunami deposition, but little or no change in the bracketing sediment occurs in association with the upper sand layer. The ages of the sand layers are not closely constrained, but were most likely deposited by tsunamis generated by great earthquakes at the Cascadia subduction zone about 1650 and 1300 years ago. The Cascadia great earthquake of AD1700 may have induced slight subsidence in the marsh, but no tsunami deposit was detected at the inferred contact. The absence of deposits from the marsh immediately inland of the 4 m-high barrier beach indicates that the largest tsunamis in the late Holocene at this site have not overtopped the barrier, which suggests that these tsunamis were likely only 2-3 m high. Close

• 13. [Article] Probabilistic Tsunami Hazard Assessment at Seaside, Oregon, for Near- and Far-Field Seismic Sources

  The first probabilistic tsunami flooding maps have been developed. The methodology, called probabilistic tsunami hazard assessment (PTHA), integrates tsunami inundation modeling with methods of probabilistic ...

  Citation × Citation Citation Abstract Copy Title: Probabilistic Tsunami Hazard Assessment at Seaside, Oregon, for Near- and Far-Field Seismic Sources Author: González, Frank, Geist, Eric L., Jaffe, Bruce, Kânoğlu, Utku, Mofjeld, Harold O., Synolakis, Costas, Titov, Vasily V., Arcas, Diego Rodriguez, Bellomo, Douglas, Carlton, David, Horning, Thomas, Johnson, Jeff, Newman, Jean, Parsons, Thomas, Peters, Robert, Peterson, Curt D., Priest, George, Venturato, Angie, Weber, Joseph, Wong, Florence L., Yalçıner, Ahmet Year: 2009 The first probabilistic tsunami flooding maps have been developed. The methodology, called probabilistic tsunami hazard assessment (PTHA), integrates tsunami inundation modeling with methods of probabilistic seismic hazard assessment (PSHA). Application of the methodology to Seaside, Oregon, has yielded estimates of the spatial distribution of 100- and 500-year maximum tsunami amplitudes, i.e., amplitudes with 1% and 0.2% annual probability of exceedance. The 100-year tsunami is generated most frequently by far-field sources in the Alaska-Aleutian Subduction Zone and is characterized by maximum amplitudes that do not exceed 4 m, with an inland extent of less than 500 m. In contrast, the 500-year tsunami is dominated by local sources in the Cascadia Subduction Zone and is characterized by maximum amplitudes in excess of 10 m and an inland extent of more than 1 km. The primary sources of uncertainty in these results include those associated with interevent time estimates, modeling of background sea level, and accounting for temporal changes in bathymetry and topography. Nonetheless, PTHA represents an important contribution to tsunami hazard assessment techniques; viewed in the broader context of risk analysis, PTHA provides a method for quantifying estimates of the likelihood and severity of the tsunami hazard, which can then be combined with vulnerability and exposure to yield estimates of tsunami risk. Title: Probabilistic Tsunami Hazard Assessment at Seaside, Oregon, for Near- and Far-Field Seismic Sources Author: González, Frank, Geist, Eric L., Jaffe, Bruce, Kânoğlu, Utku, Mofjeld, Harold O., Synolakis, Costas, Titov, Vasily V., Arcas, Diego Rodriguez, Bellomo, Douglas, Carlton, David, Horning, Thomas, Johnson, Jeff, Newman, Jean, Parsons, Thomas, Peters, Robert, Peterson, Curt D., Priest, George, Venturato, Angie, Weber, Joseph, Wong, Florence L., Yalçıner, Ahmet Year: 2009 The first probabilistic tsunami flooding maps have been developed. The methodology, called probabilistic tsunami hazard assessment (PTHA), integrates tsunami inundation modeling with methods of probabilistic seismic hazard assessment (PSHA). Application of the methodology to Seaside, Oregon, has yielded estimates of the spatial distribution of 100- and 500-year maximum tsunami amplitudes, i.e., amplitudes with 1% and 0.2% annual probability of exceedance. The 100-year tsunami is generated most frequently by far-field sources in the Alaska-Aleutian Subduction Zone and is characterized by maximum amplitudes that do not exceed 4 m, with an inland extent of less than 500 m. In contrast, the 500-year tsunami is dominated by local sources in the Cascadia Subduction Zone and is characterized by maximum amplitudes in excess of 10 m and an inland extent of more than 1 km. The primary sources of uncertainty in these results include those associated with interevent time estimates, modeling of background sea level, and accounting for temporal changes in bathymetry and topography. Nonetheless, PTHA represents an important contribution to tsunami hazard assessment techniques; viewed in the broader context of risk analysis, PTHA provides a method for quantifying estimates of the likelihood and severity of the tsunami hazard, which can then be combined with vulnerability and exposure to yield estimates of tsunami risk. Close

• 14. [Article] Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes

  Over the years, earthquakes have exposed the vulnerability of reinforced concrete structures under seismic loads. The recent occurrence of highly devastating earthquakes near instrumented regions, e.g. ...

  Citation × Citation Citation Abstract Copy Title: Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes Author: Dusicka, Peter, Bazaez, Ramiro, Knoles, Sarah Year: 2015 Over the years, earthquakes have exposed the vulnerability of reinforced concrete structures under seismic loads. The recent occurrence of highly devastating earthquakes near instrumented regions, e.g. 2010 Maule, Chile and 2011 Tohoku, Japan, has demonstrated the catastrophic impact of such natural force upon reinforced concrete structures. Research was conducted to investigate the effect of subduction zone earthquakes on structural damage. The study suggests that large magnitude ground motions of long duration have the potential of significantly increasing the number of inelastic excursions and consequently incur more extensive structural damage as compared to ground motions with similar elastic spectral demands but of shorter duration. This increase in demand plays a crucial role in the Pacific Northwest where a mega subduction zone earthquake is impending. Typical reinforced concrete bridge bents constructed in the 1950 to mid-1970 in the State of Oregon were designed and built with minimum seismic considerations. This resulted in inadequate detailing within plastic hinge zones, leaving numerous RC bents highly susceptible to damage following an earthquake. In this study, the cyclic performance of an as-built RC square column and a reinforced concrete bridge bent retrofitted using buckling restrained braces (BRBs) was experimentally evaluated using quasi-static cyclic loading protocols aiming to reflect subduction zone earthquake demands up to displacement ductility. The buckling restrained braces were designed as replaceable elements in order to take the earthquake-induced energy and dissipate it through nonlinear hysteretic behavior. Two BRB designs were considered in the study in an effort to assess the influence of BRB stiffness on the overall structural performance. The results of these large-scale experiments successfully demonstrated the effectiveness of utilizing buckling restrained braces for achieving high displacement ductility of the retrofitted structure, while also controlling the damage of the existing vulnerable reinforced concrete bent up to the design performance levels. The potential of improving the overall seismic behavior and the design performance levels with BRBs offers structural design professionals a viable method for performance driven retrofit of reinforced concrete bents. Title: Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes Author: Dusicka, Peter, Bazaez, Ramiro, Knoles, Sarah Year: 2015 Over the years, earthquakes have exposed the vulnerability of reinforced concrete structures under seismic loads. The recent occurrence of highly devastating earthquakes near instrumented regions, e.g. 2010 Maule, Chile and 2011 Tohoku, Japan, has demonstrated the catastrophic impact of such natural force upon reinforced concrete structures. Research was conducted to investigate the effect of subduction zone earthquakes on structural damage. The study suggests that large magnitude ground motions of long duration have the potential of significantly increasing the number of inelastic excursions and consequently incur more extensive structural damage as compared to ground motions with similar elastic spectral demands but of shorter duration. This increase in demand plays a crucial role in the Pacific Northwest where a mega subduction zone earthquake is impending. Typical reinforced concrete bridge bents constructed in the 1950 to mid-1970 in the State of Oregon were designed and built with minimum seismic considerations. This resulted in inadequate detailing within plastic hinge zones, leaving numerous RC bents highly susceptible to damage following an earthquake. In this study, the cyclic performance of an as-built RC square column and a reinforced concrete bridge bent retrofitted using buckling restrained braces (BRBs) was experimentally evaluated using quasi-static cyclic loading protocols aiming to reflect subduction zone earthquake demands up to displacement ductility. The buckling restrained braces were designed as replaceable elements in order to take the earthquake-induced energy and dissipate it through nonlinear hysteretic behavior. Two BRB designs were considered in the study in an effort to assess the influence of BRB stiffness on the overall structural performance. The results of these large-scale experiments successfully demonstrated the effectiveness of utilizing buckling restrained braces for achieving high displacement ductility of the retrofitted structure, while also controlling the damage of the existing vulnerable reinforced concrete bent up to the design performance levels. The potential of improving the overall seismic behavior and the design performance levels with BRBs offers structural design professionals a viable method for performance driven retrofit of reinforced concrete bents. Close

• 15. [Article] Large-Scale Fluidization Features from Late Holocene Coseismic Paleoliquefaction in the Willamette River Forearc Valley, Central Cascadia Subduction Zone, Oregon, USA

  A search of Willamette River cutbanks was conducted for the presence of late Holocene paleoli-quefaction records in the Willamette forearc valley, located 175 ± 25 km landward from the buried trench in ...

  Citation × Citation Citation Abstract Copy Title: Large-Scale Fluidization Features from Late Holocene Coseismic Paleoliquefaction in the Willamette River Forearc Valley, Central Cascadia Subduction Zone, Oregon, USA Author: Peterson, Curt D., Kristensen, Kurt, Minor, Rick Year: 2014 A search of Willamette River cutbanks was conducted for the presence of late Holocene paleoli-quefaction records in the Willamette forearc valley, located 175 ± 25 km landward from the buried trench in the central Cascadia subduction zone. A search of Willamette River cutbanks was conducted for the presence of late Holocene paleoli-quefaction records in the Willamette forearc valley, located 175 ± 25 km landward from the buried trench in the central Cascadia subduction zone. Eight cutbank sites are reported that show evidence of large-scale fluidization features (≥10 cm width) including clastic sand dikes and intruded sand sills in Holocene overbank mud deposits. The targeted alluvial sequences, and hosted paleoliquefaction records, are of late Holocene age, as based on radiocarbon dating, flood silt thickness (≤4 m thickness), and minimal consolidation of dike sand (~1.5 ± 0.5 kg·cm-2 unconfined compressive strength). Two of the paleoliquefaction sites, which are separated by 150 km distance, overlap in age (175 - 500 yr BP) with the last great megathrust rupture (Mw 8.5 - 9.0) in the Cascadia margin, dated at AD 1700. The scarcity of exposed late Holocene paleoliquefaction sites in the Willamette River cutbanks motivated subsurface searches for thick basal sand deposits and overlying fluidization features, using floodplain geomorphological analyses, ground penetrating radar, and remote pole-camera scans of deep trench walls (3 - 4 m depth). The onset of large-scale fluidization features occurred in overbank mud deposits (2 - 3 m thickness) above unconsolidated sand bodies (≥2 m thickness) with unconfined compressive strengths of ~1.5 ± 0.5 kg·cm-2. We recommend geomorphically-targeted subsurface explorations rather than traditional cutbank searches for evidence of coseismic paleoliquefaction in high-gradient river valley systems. Title: Large-Scale Fluidization Features from Late Holocene Coseismic Paleoliquefaction in the Willamette River Forearc Valley, Central Cascadia Subduction Zone, Oregon, USA Author: Peterson, Curt D., Kristensen, Kurt, Minor, Rick Year: 2014 A search of Willamette River cutbanks was conducted for the presence of late Holocene paleoli-quefaction records in the Willamette forearc valley, located 175 ± 25 km landward from the buried trench in the central Cascadia subduction zone. A search of Willamette River cutbanks was conducted for the presence of late Holocene paleoli-quefaction records in the Willamette forearc valley, located 175 ± 25 km landward from the buried trench in the central Cascadia subduction zone. Eight cutbank sites are reported that show evidence of large-scale fluidization features (≥10 cm width) including clastic sand dikes and intruded sand sills in Holocene overbank mud deposits. The targeted alluvial sequences, and hosted paleoliquefaction records, are of late Holocene age, as based on radiocarbon dating, flood silt thickness (≤4 m thickness), and minimal consolidation of dike sand (~1.5 ± 0.5 kg·cm-2 unconfined compressive strength). Two of the paleoliquefaction sites, which are separated by 150 km distance, overlap in age (175 - 500 yr BP) with the last great megathrust rupture (Mw 8.5 - 9.0) in the Cascadia margin, dated at AD 1700. The scarcity of exposed late Holocene paleoliquefaction sites in the Willamette River cutbanks motivated subsurface searches for thick basal sand deposits and overlying fluidization features, using floodplain geomorphological analyses, ground penetrating radar, and remote pole-camera scans of deep trench walls (3 - 4 m depth). The onset of large-scale fluidization features occurred in overbank mud deposits (2 - 3 m thickness) above unconsolidated sand bodies (≥2 m thickness) with unconfined compressive strengths of ~1.5 ± 0.5 kg·cm-2. We recommend geomorphically-targeted subsurface explorations rather than traditional cutbank searches for evidence of coseismic paleoliquefaction in high-gradient river valley systems. Close

• 16. [Article] Appendix C—Deformation Models for UCERF3

  This document describes efforts to best characterize seismogenic deformation in and near California. The rate of hazardous earthquakes in California is expected to be proportional to deformation rates; ...

  Citation × Citation Citation Abstract Copy Title: Appendix C—Deformation Models for UCERF3 Author: Parsons, Tom, Johnson, Kaj M., Bird, Peter, Bormann, Jayne, Dawson, Timothy E., Field, Edward H., Hammond, William C., Herring, Thomas A., McCaffrey, Robert, Shen, Zheng-kang, Thatcher, Wayne R., Weldon, Ray J., II, Zeng, Yuehua Year: 2013 This document describes efforts to best characterize seismogenic deformation in and near California. The rate of hazardous earthquakes in California is expected to be proportional to deformation rates; in particular, the rates at which faults slip. Fault slip rates are determined from offsets of geologic and geomorphic features of measured age and by modeling geodetically determined surface displacement rates. Extensive use of geodesy in the form of Global Positioning System (GPS) observations is a new feature brought into the Working Group on California Earthquake Probabilities (WGCEP) forecasts for the Uniform California Earthquake Rupture Forecast, version 3 (UCERF3) model. Geodetic measurements are potentially more spatially comprehensive than geologic offset observations, which can be clustered. Applying either type of data is subject to considerable uncertainty. Geologic observations have dating and other measurement errors, and they often must be extrapolated long distances on fault sections. However, geodetic observations require a modeling step to translate them into estimates of fault slip rate, and they have poor resolution on closely spaced, locked faults. Details about fault slip rates from geologic offsets are presented in appendix B (this report). In this appendix we look at three deformation models that use geologic and geodetic constraints and compare/contrast them with the UCERF3 geological model and the UCERF2 deformation model. We present models, results, and evaluation for their use in the UCERF3 forecast. Title: Appendix C—Deformation Models for UCERF3 Author: Parsons, Tom, Johnson, Kaj M., Bird, Peter, Bormann, Jayne, Dawson, Timothy E., Field, Edward H., Hammond, William C., Herring, Thomas A., McCaffrey, Robert, Shen, Zheng-kang, Thatcher, Wayne R., Weldon, Ray J., II, Zeng, Yuehua Year: 2013 This document describes efforts to best characterize seismogenic deformation in and near California. The rate of hazardous earthquakes in California is expected to be proportional to deformation rates; in particular, the rates at which faults slip. Fault slip rates are determined from offsets of geologic and geomorphic features of measured age and by modeling geodetically determined surface displacement rates. Extensive use of geodesy in the form of Global Positioning System (GPS) observations is a new feature brought into the Working Group on California Earthquake Probabilities (WGCEP) forecasts for the Uniform California Earthquake Rupture Forecast, version 3 (UCERF3) model. Geodetic measurements are potentially more spatially comprehensive than geologic offset observations, which can be clustered. Applying either type of data is subject to considerable uncertainty. Geologic observations have dating and other measurement errors, and they often must be extrapolated long distances on fault sections. However, geodetic observations require a modeling step to translate them into estimates of fault slip rate, and they have poor resolution on closely spaced, locked faults. Details about fault slip rates from geologic offsets are presented in appendix B (this report). In this appendix we look at three deformation models that use geologic and geodetic constraints and compare/contrast them with the UCERF3 geological model and the UCERF2 deformation model. We present models, results, and evaluation for their use in the UCERF3 forecast. Close

• 17. [Article] Cyclic Behavior of Reinforced Concrete Bridge Bent Retrofitted with Buckling Restrained Braces

  The cyclic behavior of a deficient reinforced concrete bridge bent retrofitted using buckling restrained braces (BRBs) was experimentally evaluated using large scale experiments and quasi-static cyclic ...

  Citation × Citation Citation Abstract Copy Title: Cyclic Behavior of Reinforced Concrete Bridge Bent Retrofitted with Buckling Restrained Braces Author: Bazaez, Ramiro, Dusicka, Peter Year: 2016 The cyclic behavior of a deficient reinforced concrete bridge bent retrofitted using buckling restrained braces (BRBs) was experimentally evaluated using large scale experiments and quasi-static cyclic loading that reflected subduction zone earthquake demands. The retrofitted reinforced concrete bent specimen consisted of two circular cross section columns, a rectangular cap beam and a buckling restrained brace in a diagonal configuration. The brace was secured to the bent using steel gusset plates and post-installed adhesive anchors. The retrofitted bent was designed to perform elastically or with minor damage under different seismic hazards design levels. Two BRB designs were considered in an effort to assess the influence of the BRB design on the overall bent performance. The data from these large-scale experiments were analyzed considering bent hysteretic response, observed damage, component curvatures, internal member loads, as well as the overall stiffness and energy dissipation characteristics. The results successfully demonstrated the effectiveness of utilizing buckling restrained braces for achieving high displacement ductility of the retrofitted structure, while also controlling the damage of the existing vulnerable reinforced concrete bent. No damage was observed in the connection regions of the brace throughout the loading history, leaving the potential for rapid replaceability of the sacrificial BRB element. Title: Cyclic Behavior of Reinforced Concrete Bridge Bent Retrofitted with Buckling Restrained Braces Author: Bazaez, Ramiro, Dusicka, Peter Year: 2016 The cyclic behavior of a deficient reinforced concrete bridge bent retrofitted using buckling restrained braces (BRBs) was experimentally evaluated using large scale experiments and quasi-static cyclic loading that reflected subduction zone earthquake demands. The retrofitted reinforced concrete bent specimen consisted of two circular cross section columns, a rectangular cap beam and a buckling restrained brace in a diagonal configuration. The brace was secured to the bent using steel gusset plates and post-installed adhesive anchors. The retrofitted bent was designed to perform elastically or with minor damage under different seismic hazards design levels. Two BRB designs were considered in an effort to assess the influence of the BRB design on the overall bent performance. The data from these large-scale experiments were analyzed considering bent hysteretic response, observed damage, component curvatures, internal member loads, as well as the overall stiffness and energy dissipation characteristics. The results successfully demonstrated the effectiveness of utilizing buckling restrained braces for achieving high displacement ductility of the retrofitted structure, while also controlling the damage of the existing vulnerable reinforced concrete bent. No damage was observed in the connection regions of the brace throughout the loading history, leaving the potential for rapid replaceability of the sacrificial BRB element. Close

• 18. [Article] Current Perspectives on Energy and Mass Fluxes in Volcanic Arcs

  Volcanoes of the Pacific Ring of Fire and other convergent margins worldwide are familiar manifestations of nature's energy, account for about 25% of global volcanic outputs, dominate volcanic gas emissions ...

  Citation × Citation Citation Abstract Copy Title: Current Perspectives on Energy and Mass Fluxes in Volcanic Arcs Author: Leeman, William, Davidson, Jon, Fischer, Tobias, Grunder, Anita, Reagan, Mark, Streck, Martin J. Year: 2003 Volcanoes of the Pacific Ring of Fire and other convergent margins worldwide are familiar manifestations of nature's energy, account for about 25% of global volcanic outputs, dominate volcanic gas emissions to the atmosphere, and pose significant physical threats to a large human population. Yet the processes behind this prolific activity remain poorly understood. An international "State of the Arc" (SOTA) conference was held in August on the slopes of Mt. Hood, Oregon, to address current views on the energy and mass fluxes in volcanic arcs. This meeting brought together some 90 leading experts and students of subduction zones and their related magmatism. Title: Current Perspectives on Energy and Mass Fluxes in Volcanic Arcs Author: Leeman, William, Davidson, Jon, Fischer, Tobias, Grunder, Anita, Reagan, Mark, Streck, Martin J. Year: 2003 Volcanoes of the Pacific Ring of Fire and other convergent margins worldwide are familiar manifestations of nature's energy, account for about 25% of global volcanic outputs, dominate volcanic gas emissions to the atmosphere, and pose significant physical threats to a large human population. Yet the processes behind this prolific activity remain poorly understood. An international "State of the Arc" (SOTA) conference was held in August on the slopes of Mt. Hood, Oregon, to address current views on the energy and mass fluxes in volcanic arcs. This meeting brought together some 90 leading experts and students of subduction zones and their related magmatism. Close

• 19. [Article] GPS Constraints on the Mw = 7.5 Ometepec Earthquake Sequence, Southern Mexico: Coseismic and Post-Seismic Deformation

  We use continuous GPS measurements from 31 stations in southernMexico to model coseismic slip and post-seismic deformation from the 2012 March 20 Mw = 7.5 Ometepec earthquake, the first large thrust earthquake ...

  Citation × Citation Citation Abstract Copy Title: GPS Constraints on the Mw = 7.5 Ometepec Earthquake Sequence, Southern Mexico: Coseismic and Post-Seismic Deformation Author: Graham, Shannon E., DeMets, Charles, Cabral-Cano, Enrique, Kostoglodov, Vladimir, Walpersdorf, Andrea, Cotte, Nathalie, Brudzinski, Michael, McCaffrey, Robert, Salazar-Tlaczani, Luis Year: 2014 We use continuous GPS measurements from 31 stations in southernMexico to model coseismic slip and post-seismic deformation from the 2012 March 20 Mw = 7.5 Ometepec earthquake, the first large thrust earthquake to occur below central Mexico during the modern GPS era. Coseismic offsets ranging from ∼280 mm near the epicentre to 5 mm or less at sites far from the epicentre are fit best by a rupture focused between ∼15 and 35 km depth, consistent with an independent seismological estimate. The corresponding geodetic moment of 1.4 × 1020 N·m is within 10 per cent of two independent seismic estimates. Transient post-seismic motion recorded by GPS sites as far as 300 km from the rupture has a different horizontal deformation gradient and opposite sense of vertical motion than do the coseismic offsets. A forward model of viscoelastic relaxation as a result of our new coseismic slip solution incorrectly predicts uplift in areas where post-seismic subsidence was recorded and indicates that viscoelastic deformation was no more than a few per cent of the measured post-seismic deformation. The deformation within 6 months of the earthquake was thus strongly dominated by fault afterslip. The post-seismic GPS time-series are well fit as logarithmically decaying fault afterslip on an area of the subduction interface up to 10 times larger than the earthquake rupture zone, extending as far as 220 km inland. Afterslip had a cumulative geodetic moment of 2.0 × 1020 N·m, ∼40 per cent larger than the Ometepec earthquake. Tests for the shallow and deep limits for the afterslip require that it included much of the earthquake rupture zone as well as regions of the subduction interface where slow slip events and non-volcanic tremor have been recorded and areas even farther downdip on the flat interface. Widespread afterslip below much of central Mexico suggests that most of the nearly flat subduction interface in this region is conditionally stable and thus contributes measurable transient deformation to large areas of Mexico south of and in the volcanic belt. Title: GPS Constraints on the Mw = 7.5 Ometepec Earthquake Sequence, Southern Mexico: Coseismic and Post-Seismic Deformation Author: Graham, Shannon E., DeMets, Charles, Cabral-Cano, Enrique, Kostoglodov, Vladimir, Walpersdorf, Andrea, Cotte, Nathalie, Brudzinski, Michael, McCaffrey, Robert, Salazar-Tlaczani, Luis Year: 2014 We use continuous GPS measurements from 31 stations in southernMexico to model coseismic slip and post-seismic deformation from the 2012 March 20 Mw = 7.5 Ometepec earthquake, the first large thrust earthquake to occur below central Mexico during the modern GPS era. Coseismic offsets ranging from ∼280 mm near the epicentre to 5 mm or less at sites far from the epicentre are fit best by a rupture focused between ∼15 and 35 km depth, consistent with an independent seismological estimate. The corresponding geodetic moment of 1.4 × 1020 N·m is within 10 per cent of two independent seismic estimates. Transient post-seismic motion recorded by GPS sites as far as 300 km from the rupture has a different horizontal deformation gradient and opposite sense of vertical motion than do the coseismic offsets. A forward model of viscoelastic relaxation as a result of our new coseismic slip solution incorrectly predicts uplift in areas where post-seismic subsidence was recorded and indicates that viscoelastic deformation was no more than a few per cent of the measured post-seismic deformation. The deformation within 6 months of the earthquake was thus strongly dominated by fault afterslip. The post-seismic GPS time-series are well fit as logarithmically decaying fault afterslip on an area of the subduction interface up to 10 times larger than the earthquake rupture zone, extending as far as 220 km inland. Afterslip had a cumulative geodetic moment of 2.0 × 1020 N·m, ∼40 per cent larger than the Ometepec earthquake. Tests for the shallow and deep limits for the afterslip require that it included much of the earthquake rupture zone as well as regions of the subduction interface where slow slip events and non-volcanic tremor have been recorded and areas even farther downdip on the flat interface. Widespread afterslip below much of central Mexico suggests that most of the nearly flat subduction interface in this region is conditionally stable and thus contributes measurable transient deformation to large areas of Mexico south of and in the volcanic belt. Close

• 20. [Article] Earthquake and Tsunami Forecasts: Relation of Slow Slip Events to Subsequent Earthquake Rupture

  The 5 September 2012 Mw 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. High-precision GPS recorded numerous slow slip events (SSEs) in the decade leading ...

  Citation × Citation Citation Abstract Copy Title: Earthquake and Tsunami Forecasts: Relation of Slow Slip Events to Subsequent Earthquake Rupture Author: Dixon, Timothy H., Jiang, Yan, Malservisi, Rocco, McCaffrey, Robert, Voss, Nicholas, Protti, Marino, Gonzalez, Victor Year: 2014 The 5 September 2012 Mw 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. High-precision GPS recorded numerous slow slip events (SSEs) in the decade leading up to the earthquake, both up-dip and down-dip of seismic rupture. Deeper SSEs were larger than shallower ones and, if characteristic of the interseismic period, release most locking down-dip of the earthquake, limiting down-dip rupture and earthquake magnitude. Shallower SSEs were smaller, accounting for some but not all interseismic locking. One SSE occurred several months before the earthquake, but changes in Mohr–Coulomb failure stress were probably too small to trigger the earthquake. Because many SSEs have occurred without subsequent rupture, their individual predictive value is limited, but taken together they released a significant amount of accumulated interseismic strain before the earthquake, effectively defining the area of subsequent seismic rupture (rupture did not occur where slow slip was common). Because earthquake magnitude depends on rupture area, this has important implications for earthquake hazard assessment. Specifically, if this behavior is representative of future earthquake cycles and other subduction zones, it implies that monitoring SSEs, including shallow up-dip events that lie offshore, could lead to accurate forecasts of earthquake magnitude and tsunami potential. Title: Earthquake and Tsunami Forecasts: Relation of Slow Slip Events to Subsequent Earthquake Rupture Author: Dixon, Timothy H., Jiang, Yan, Malservisi, Rocco, McCaffrey, Robert, Voss, Nicholas, Protti, Marino, Gonzalez, Victor Year: 2014 The 5 September 2012 Mw 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. High-precision GPS recorded numerous slow slip events (SSEs) in the decade leading up to the earthquake, both up-dip and down-dip of seismic rupture. Deeper SSEs were larger than shallower ones and, if characteristic of the interseismic period, release most locking down-dip of the earthquake, limiting down-dip rupture and earthquake magnitude. Shallower SSEs were smaller, accounting for some but not all interseismic locking. One SSE occurred several months before the earthquake, but changes in Mohr–Coulomb failure stress were probably too small to trigger the earthquake. Because many SSEs have occurred without subsequent rupture, their individual predictive value is limited, but taken together they released a significant amount of accumulated interseismic strain before the earthquake, effectively defining the area of subsequent seismic rupture (rupture did not occur where slow slip was common). Because earthquake magnitude depends on rupture area, this has important implications for earthquake hazard assessment. Specifically, if this behavior is representative of future earthquake cycles and other subduction zones, it implies that monitoring SSEs, including shallow up-dip events that lie offshore, could lead to accurate forecasts of earthquake magnitude and tsunami potential. Close

• 21. [Article] Interseismic Locking on the Hikurangi Subduction Zone: Uncertainties from Slow-Slip Events

  lnterseismic locking on the Hikurangi subduction zone in New Zealand is examined in light of alternative assumed locking distributions and the impact of transients (slow-slip and volcanic sources) on temporal ...

  Citation × Citation Citation Abstract Copy Title: Interseismic Locking on the Hikurangi Subduction Zone: Uncertainties from Slow-Slip Events Author: McCaffrey, Robert Year: 2014 lnterseismic locking on the Hikurangi subduction zone in New Zealand is examined in light of alternative assumed locking distributions and the impact of transients (slow-slip and volcanic sources) on temporal and spatial resolution. The modern pattern of locking in the north is poorly resolved and, based on simulations of possible transient behavior, may be an ephemeral feature of the subduction cycle. While there appears to be some contemporary locking in the northern half of the Hikurangi subduction zone (HSZ), its location is model dependent, and hence, its relationship to structure, slow-slip, or any transition zone there is unclear. Simulations of site velocities using the 14 year history of transient events reveal that in the timescale of the interseismic period the northern half of the HSZ could be either locked or unlocked, and this may not be resolvable for decades. In the southern half, there is strong contemporary locking in the 15 to 40 km depth range, but again, the slow-slip history leads to uncertainty in the long-term pattern. Slow-slip events not only reduce the long-term locking by aseismic slip but also greatly hinder our ability to see it. It is within the range of possible models that the slip deficit rate at the HSZ is more uniform along strike, and the modern appearance is controlled by the particular pattern of transients over the past 10 to 20 years when the GPS data were collected. Similarly, uncertainties in surface velocities will be large at any subduction zone with large transients. Title: Interseismic Locking on the Hikurangi Subduction Zone: Uncertainties from Slow-Slip Events Author: McCaffrey, Robert Year: 2014 lnterseismic locking on the Hikurangi subduction zone in New Zealand is examined in light of alternative assumed locking distributions and the impact of transients (slow-slip and volcanic sources) on temporal and spatial resolution. The modern pattern of locking in the north is poorly resolved and, based on simulations of possible transient behavior, may be an ephemeral feature of the subduction cycle. While there appears to be some contemporary locking in the northern half of the Hikurangi subduction zone (HSZ), its location is model dependent, and hence, its relationship to structure, slow-slip, or any transition zone there is unclear. Simulations of site velocities using the 14 year history of transient events reveal that in the timescale of the interseismic period the northern half of the HSZ could be either locked or unlocked, and this may not be resolvable for decades. In the southern half, there is strong contemporary locking in the 15 to 40 km depth range, but again, the slow-slip history leads to uncertainty in the long-term pattern. Slow-slip events not only reduce the long-term locking by aseismic slip but also greatly hinder our ability to see it. It is within the range of possible models that the slip deficit rate at the HSZ is more uniform along strike, and the modern appearance is controlled by the particular pattern of transients over the past 10 to 20 years when the GPS data were collected. Similarly, uncertainties in surface velocities will be large at any subduction zone with large transients. Close

• 22. [Article] Central Cascadia Subduction Zone Creep

  Central Cascadia between 43ºN and 46ºN has reduced interseismic uplift observed in geodetic data and coseismic subsidence seen in multiple thrust earthquakes, suggesting elevated persistent fault creep ...

  Citation × Citation Citation Abstract Copy Title: Central Cascadia Subduction Zone Creep Author: Schmalzle, Gina M., McCaffrey, Robert, Creager, Kenneth C. Year: 2014 Central Cascadia between 43ºN and 46ºN has reduced interseismic uplift observed in geodetic data and coseismic subsidence seen in multiple thrust earthquakes, suggesting elevated persistent fault creep in this section of the subduction zone. We estimate subduction thrust "decade-scale" locking and crustal block rotations from three-component continuous Global Positioning System (GPS) time series from 1997 to 2013, as well as 80 year tide gauge and leveling-derived uplift rates. Geodetic observations indicatecoastal central Oregon is rising at a slower rate than coastal Washington, southern Oregon and northern California. Modeled locking distributions suggest a wide locking transition zone that extends inland undercentral Oregon. Paleoseismic records of multiple great earthquakes along Cascadia indicate less subsidence in central Oregon. The Cascade thrust under central Oregon may be partially creeping for at least 6500 years(the length of the paleoseismic record) reducing interseismic uplift and resulting in reduced coseismic subsidence. Large accretions of Eocene age basalt (Siletzia terrane) between 43ºN and 46ºN may be less perme-able compared to surrounding terranes, potentially increasing pore fluid pressures along the fault interface resulting in a wide zone of persistent fault creep. In a separate inversion, three-component GPS time series from 1 July 2005 to 1 January 2011 are used to estimate upper plate deformation, locking between slow-slip events (SSEs), slip from 16 SSEs and an earthquake mechanism. Cumulative SSEs and tectonic tremor are weakest between 43ºN and 46ºN where partial fault creep is increased and Siletzia terrane is thick, suggesting that surrounding rock properties may influence the mode of slip. Title: Central Cascadia Subduction Zone Creep Author: Schmalzle, Gina M., McCaffrey, Robert, Creager, Kenneth C. Year: 2014 Central Cascadia between 43ºN and 46ºN has reduced interseismic uplift observed in geodetic data and coseismic subsidence seen in multiple thrust earthquakes, suggesting elevated persistent fault creep in this section of the subduction zone. We estimate subduction thrust "decade-scale" locking and crustal block rotations from three-component continuous Global Positioning System (GPS) time series from 1997 to 2013, as well as 80 year tide gauge and leveling-derived uplift rates. Geodetic observations indicatecoastal central Oregon is rising at a slower rate than coastal Washington, southern Oregon and northern California. Modeled locking distributions suggest a wide locking transition zone that extends inland undercentral Oregon. Paleoseismic records of multiple great earthquakes along Cascadia indicate less subsidence in central Oregon. The Cascade thrust under central Oregon may be partially creeping for at least 6500 years(the length of the paleoseismic record) reducing interseismic uplift and resulting in reduced coseismic subsidence. Large accretions of Eocene age basalt (Siletzia terrane) between 43ºN and 46ºN may be less perme-able compared to surrounding terranes, potentially increasing pore fluid pressures along the fault interface resulting in a wide zone of persistent fault creep. In a separate inversion, three-component GPS time series from 1 July 2005 to 1 January 2011 are used to estimate upper plate deformation, locking between slow-slip events (SSEs), slip from 16 SSEs and an earthquake mechanism. Cumulative SSEs and tectonic tremor are weakest between 43ºN and 46ºN where partial fault creep is increased and Siletzia terrane is thick, suggesting that surrounding rock properties may influence the mode of slip. Close

• 23. [Article] Achieving Operational Seismic Performance of RC Bridge Bents Retrofitted With Buckling-Restrained Braces

  Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to ...

  Citation × Citation Citation Abstract Copy Title: Achieving Operational Seismic Performance of RC Bridge Bents Retrofitted With Buckling-Restrained Braces Author: Bazáez Gallardo, Ramiro Andrés Gabriel Year: 2017 Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity of RC bridge columns and change their failure mode. The cyclic performance of reinforced concrete bridge bents retrofitted and repaired using BRBs was experimentally evaluated using large-scale specimens and the developed loading histories. Three BRB specimens were evaluated with the aim of assessing the influence of these components on the overall performance of the retrofitted and repaired bents. Additionally, subassemblage tests were conducted in an effort to study the response of these elements and to allow for refined nonlinear characterization in the analysis of the retrofitted and repaired systems. The results of the large-scale experiments and analytical studies successfully demonstrated the effectiveness of utilizing buckling-restrained braces for achieving high displacement ductility of the retrofitted and repaired structures, while also controlling the damage of the existing vulnerable reinforced concrete bent up to an operational performance level. Title: Achieving Operational Seismic Performance of RC Bridge Bents Retrofitted With Buckling-Restrained Braces Author: Bazáez Gallardo, Ramiro Andrés Gabriel Year: 2017 Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity of RC bridge columns and change their failure mode. The cyclic performance of reinforced concrete bridge bents retrofitted and repaired using BRBs was experimentally evaluated using large-scale specimens and the developed loading histories. Three BRB specimens were evaluated with the aim of assessing the influence of these components on the overall performance of the retrofitted and repaired bents. Additionally, subassemblage tests were conducted in an effort to study the response of these elements and to allow for refined nonlinear characterization in the analysis of the retrofitted and repaired systems. The results of the large-scale experiments and analytical studies successfully demonstrated the effectiveness of utilizing buckling-restrained braces for achieving high displacement ductility of the retrofitted and repaired structures, while also controlling the damage of the existing vulnerable reinforced concrete bent up to an operational performance level. Close

• 24. [Article] Establishing the Inundation Distance and Overtopping Height of Paleotsunami from the Late-Holocene Geologic Record at Open-Coastal Wetland Sites, Central Cascadia Margin

  Mapping and stratigraphic investigations of back barrier, open-coastal plain sites have been used to establish minimum inundation distances and wave heights of tsunami produced by great subduction zone ...

  Citation × Citation Citation Abstract Copy Title: Establishing the Inundation Distance and Overtopping Height of Paleotsunami from the Late-Holocene Geologic Record at Open-Coastal Wetland Sites, Central Cascadia Margin Author: Schlichting, Robert B. Year: 2000 Mapping and stratigraphic investigations of back barrier, open-coastal plain sites have been used to establish minimum inundation distances and wave heights of tsunami produced by great subduction zone earthquakes in the central Cascadia margin. Cascadia tsunami deposits have been reported for many coseismic subsidence events in bay marsh settings where tidal-channel features focus tsunami energy. Variable magnitude (8.5±0.5 Mw), frequency (500±300 yr recurrence), and rupture geometry produce widely varying computer model outcomes for Casdcadia tsunami inundation. The results presented in this thesis provide specific quantitative data regarding tsunami inundation at the open coast. Anomalous sand sheets that have been characterized consist of well-sorted beach sand that fine up-section. The thickness of the deposits vary from 45 em to 0.2 em, and thin in the landward direction. Many of the sand layers include detrital caps. One to three detritus and mud lamina are intra-layered in the deposits. Marine diatoms and bromine, a marine tracer, increase in concentration at each of the sand layers. Title: Establishing the Inundation Distance and Overtopping Height of Paleotsunami from the Late-Holocene Geologic Record at Open-Coastal Wetland Sites, Central Cascadia Margin Author: Schlichting, Robert B. Year: 2000 Mapping and stratigraphic investigations of back barrier, open-coastal plain sites have been used to establish minimum inundation distances and wave heights of tsunami produced by great subduction zone earthquakes in the central Cascadia margin. Cascadia tsunami deposits have been reported for many coseismic subsidence events in bay marsh settings where tidal-channel features focus tsunami energy. Variable magnitude (8.5±0.5 Mw), frequency (500±300 yr recurrence), and rupture geometry produce widely varying computer model outcomes for Casdcadia tsunami inundation. The results presented in this thesis provide specific quantitative data regarding tsunami inundation at the open coast. Anomalous sand sheets that have been characterized consist of well-sorted beach sand that fine up-section. The thickness of the deposits vary from 45 em to 0.2 em, and thin in the landward direction. Many of the sand layers include detrital caps. One to three detritus and mud lamina are intra-layered in the deposits. Marine diatoms and bromine, a marine tracer, increase in concentration at each of the sand layers. Close

• 25. [Article] A Morphologic Proxy for Debris Flow Erosion With Application to the Earthquake Deformation Cycle, Cascadia Subduction Zone, USA

  In unglaciated steeplands, valley reaches dominated by debris flow scour and incision set landscape form as they often account for > 80% of valley network length and relief. While hillslope and fluvial ...

  Citation × Citation Citation Abstract Copy Title: A Morphologic Proxy for Debris Flow Erosion With Application to the Earthquake Deformation Cycle, Cascadia Subduction Zone, USA Author: Penserini, Brian D., Roering, Joshua J., Strieg, Ashley Year: 2017 In unglaciated steeplands, valley reaches dominated by debris flow scour and incision set landscape form as they often account for > 80% of valley network length and relief. While hillslope and fluvial process models have frequently been combined with digital topography to develop morphologic proxies for erosion rate and drainage divide migration, debris-flow-dominated networks, despite their ubiquity, have not been exploited for this purpose. Here, we applied an empirical function that describes how slope-area data systematically deviate from so-called fluvial power-law behavior at small drainage areas. Using airborne LiDAR data for 83 small (~ 1 km2) catchments in the western Oregon Coast Range, we quantified variation in model parameters and observed that the curvature of the power-law scaling deviation varies with catchment-averaged erosion rate estimated from cosmogenic nuclides in stream sediments. Given consistent climate and lithology across our study area and assuming steady erosion, we used this calibrated denudation-morphology relationship to map spatial patterns of long-term uplift for our study catchments. By combining our predicted pattern of long-term uplift rate with paleoseismic and geodetic (tide gauge, GPS, and leveling) data, we estimated the spatial distribution of coseismic subsidence experienced during megathrust earthquakes along the Cascadia Subduction Zone. Our estimates of coseismic subsidence near the coast (0.4 to 0.7 m for earthquake recurrence intervals of 300 to 500 years) agree with field measurements from numerous stratigraphic studies. Our results also demonstrate that coseismic subsidence decreases inland to negligible values > 25 km from the coast, reflecting the diminishing influence of the earthquake deformation cycle on vertical changes of the interior coastal ranges. More generally, our results demonstrate that debris flow valley networks serve as highly localized, yet broadly distributed indicators of erosion (and rock uplift), making them invaluable for mapping crustal deformation and landscape adjustment. © 2017 Elsevier B.V. Title: A Morphologic Proxy for Debris Flow Erosion With Application to the Earthquake Deformation Cycle, Cascadia Subduction Zone, USA Author: Penserini, Brian D., Roering, Joshua J., Strieg, Ashley Year: 2017 In unglaciated steeplands, valley reaches dominated by debris flow scour and incision set landscape form as they often account for > 80% of valley network length and relief. While hillslope and fluvial process models have frequently been combined with digital topography to develop morphologic proxies for erosion rate and drainage divide migration, debris-flow-dominated networks, despite their ubiquity, have not been exploited for this purpose. Here, we applied an empirical function that describes how slope-area data systematically deviate from so-called fluvial power-law behavior at small drainage areas. Using airborne LiDAR data for 83 small (~ 1 km2) catchments in the western Oregon Coast Range, we quantified variation in model parameters and observed that the curvature of the power-law scaling deviation varies with catchment-averaged erosion rate estimated from cosmogenic nuclides in stream sediments. Given consistent climate and lithology across our study area and assuming steady erosion, we used this calibrated denudation-morphology relationship to map spatial patterns of long-term uplift for our study catchments. By combining our predicted pattern of long-term uplift rate with paleoseismic and geodetic (tide gauge, GPS, and leveling) data, we estimated the spatial distribution of coseismic subsidence experienced during megathrust earthquakes along the Cascadia Subduction Zone. Our estimates of coseismic subsidence near the coast (0.4 to 0.7 m for earthquake recurrence intervals of 300 to 500 years) agree with field measurements from numerous stratigraphic studies. Our results also demonstrate that coseismic subsidence decreases inland to negligible values > 25 km from the coast, reflecting the diminishing influence of the earthquake deformation cycle on vertical changes of the interior coastal ranges. More generally, our results demonstrate that debris flow valley networks serve as highly localized, yet broadly distributed indicators of erosion (and rock uplift), making them invaluable for mapping crustal deformation and landscape adjustment. © 2017 Elsevier B.V. Close

• 26. [Article] Slow Slip Events and Time-Dependent Variations in Locking Beneath Lower Cook Inlet of the Alaska-Aleutian Subduction Zone

  We identify a series of abrupt changes in GPS site velocities in Lower Cook Inlet, Alaska, in late 2004, early 2010, and late 2011. The site motions during each time period are nearly linear. The surface ...

  Citation × Citation Citation Abstract Copy Title: Slow Slip Events and Time-Dependent Variations in Locking Beneath Lower Cook Inlet of the Alaska-Aleutian Subduction Zone Author: Li, Shanshan, Freymueller, Jeffrey, McCaffrey, Robert Year: 2016 We identify a series of abrupt changes in GPS site velocities in Lower Cook Inlet, Alaska, in late 2004, early 2010, and late 2011. The site motions during each time period are nearly linear. The surface deformations inferred from GPS for pre-2004 and 2010–2011 are similar to each other, as are 2004–2010 and post-2011. We estimate the slip distribution on the Alaska-Aleutian subduction plate interface accounting for upper plate block rotations and interpret this toggling between two deformation patterns as caused by transient slip. We find that by allowing negative slip deficit rates (i.e., creep rates in excess of relative plate motion), the data in Lower Cook Inlet are fit significantly better during pre-2004 and 2010–2011, suggesting the occurrence of slow slip events (SSEs) there during those time periods. The earlier SSE lasted at least 9 years (observations in that area began in 1995) with Mw ~7.8. The latter SSE had almost the same area as the earlier one and a duration of ~2 years with Mw ~7.2. During 2004–2010 and post-2011, the inversions result in only positive slip deficit rates (i.e., locking) in Lower Cook Inlet. Slip rates are nearly constant during the Lower Cook Inlet SSEs, and the events start and stop abruptly. Both of these properties contrast with observations of SSEs in Upper Cook Inlet and elsewhere. The Lower Cook Inlet SSEs are consistent with previously proposed duration-magnitude scaling laws and demonstrate that slow slip events can last as long as a decade. Title: Slow Slip Events and Time-Dependent Variations in Locking Beneath Lower Cook Inlet of the Alaska-Aleutian Subduction Zone Author: Li, Shanshan, Freymueller, Jeffrey, McCaffrey, Robert Year: 2016 We identify a series of abrupt changes in GPS site velocities in Lower Cook Inlet, Alaska, in late 2004, early 2010, and late 2011. The site motions during each time period are nearly linear. The surface deformations inferred from GPS for pre-2004 and 2010–2011 are similar to each other, as are 2004–2010 and post-2011. We estimate the slip distribution on the Alaska-Aleutian subduction plate interface accounting for upper plate block rotations and interpret this toggling between two deformation patterns as caused by transient slip. We find that by allowing negative slip deficit rates (i.e., creep rates in excess of relative plate motion), the data in Lower Cook Inlet are fit significantly better during pre-2004 and 2010–2011, suggesting the occurrence of slow slip events (SSEs) there during those time periods. The earlier SSE lasted at least 9 years (observations in that area began in 1995) with Mw ~7.8. The latter SSE had almost the same area as the earlier one and a duration of ~2 years with Mw ~7.2. During 2004–2010 and post-2011, the inversions result in only positive slip deficit rates (i.e., locking) in Lower Cook Inlet. Slip rates are nearly constant during the Lower Cook Inlet SSEs, and the events start and stop abruptly. Both of these properties contrast with observations of SSEs in Upper Cook Inlet and elsewhere. The Lower Cook Inlet SSEs are consistent with previously proposed duration-magnitude scaling laws and demonstrate that slow slip events can last as long as a decade. Close

• 27. [Article] Multiple Reoccupations after Four Paleotsunami Inundations (0.3–1.3 ka) at a Prehistoric Site in the Netarts Littoral Cell, Northern Oregon Coast, USA

  Netarts Bay is the setting of one of the largest concentrations of late prehistoric Native American settlements on the tectonically active Oregon coast. A prehistoric site (35TI74) exposed by sea cliff ...

  Citation × Citation Citation Abstract Copy Title: Multiple Reoccupations after Four Paleotsunami Inundations (0.3–1.3 ka) at a Prehistoric Site in the Netarts Littoral Cell, Northern Oregon Coast, USA Author: Minor, Rick, Peterson, Curt D. Year: 2017 Netarts Bay is the setting of one of the largest concentrations of late prehistoric Native American settlements on the tectonically active Oregon coast. A prehistoric site (35TI74) exposed by sea cliff erosion in 1998 at the south end of the Netarts littoral cell contained a stratigraphic record of activity by prehistoric Native Americans and interbedded paleotsunami deposits. The nearfield paleotsunamis were produced by great Cascadia earthquakes (Mw8.5 ± 0.5) emanating from the Cascadia Subduction Zone offshore, as previously documented in episodically buried tidal marsh surfaces at the south end of Netarts Bay and in many other estuaries in the region. The cultural deposits at 35TI74 reflect multiple reoccupations by Native Americans at this barrage creek flood plain site between paleotsunami runup events (≥7.5 m elevation) at 1.3 ka, 1.1 ka, 0.8–0.9 ka, and 0.3 ka. The conditions that led to the exposure of 35TI74 are traced to erosion of a protective beach dune ramp at the south end of the Netarts littoral cell, placing the site within reach of progressive storm-surf erosion. The diminishing geoarchaeological record at 35TI74 represents a microcosm of the sea cliff erosional processes that threaten vulnerable prehistoric shoreline archaeological sites along much of the Pacific Northwest Coast. Copyright © 2016 Wiley Periodicals, Inc. Title: Multiple Reoccupations after Four Paleotsunami Inundations (0.3–1.3 ka) at a Prehistoric Site in the Netarts Littoral Cell, Northern Oregon Coast, USA Author: Minor, Rick, Peterson, Curt D. Year: 2017 Netarts Bay is the setting of one of the largest concentrations of late prehistoric Native American settlements on the tectonically active Oregon coast. A prehistoric site (35TI74) exposed by sea cliff erosion in 1998 at the south end of the Netarts littoral cell contained a stratigraphic record of activity by prehistoric Native Americans and interbedded paleotsunami deposits. The nearfield paleotsunamis were produced by great Cascadia earthquakes (Mw8.5 ± 0.5) emanating from the Cascadia Subduction Zone offshore, as previously documented in episodically buried tidal marsh surfaces at the south end of Netarts Bay and in many other estuaries in the region. The cultural deposits at 35TI74 reflect multiple reoccupations by Native Americans at this barrage creek flood plain site between paleotsunami runup events (≥7.5 m elevation) at 1.3 ka, 1.1 ka, 0.8–0.9 ka, and 0.3 ka. The conditions that led to the exposure of 35TI74 are traced to erosion of a protective beach dune ramp at the south end of the Netarts littoral cell, placing the site within reach of progressive storm-surf erosion. The diminishing geoarchaeological record at 35TI74 represents a microcosm of the sea cliff erosional processes that threaten vulnerable prehistoric shoreline archaeological sites along much of the Pacific Northwest Coast. Copyright © 2016 Wiley Periodicals, Inc. Close

• 28. [Article] Tsunami Hydrodynamics in the Columbia River

  On 11 March 2011, the Tohoku Tsunami overtopped a weir and penetrated 49 km up the Kitakami River, the fourth largest river in Japan. Similarly, the 2010 Chile tsunami propagated at least 15 km up the ...

  Citation × Citation Citation Abstract Copy Title: Tsunami Hydrodynamics in the Columbia River Author: Yeh, Harry, Tolkova, Elena, Jay, David A., Talke, Stefan A., Fritz, Hermann Year: 2012 On 11 March 2011, the Tohoku Tsunami overtopped a weir and penetrated 49 km up the Kitakami River, the fourth largest river in Japan. Similarly, the 2010 Chile tsunami propagated at least 15 km up the Maule River. In the Pacific Northwest of the United States, large tsunamis have occurred along the Cascadia subduction zone, most recently the 'orphan tsunami' of 1700 (Atwater et al.). The expected future occurrence of a Cascadia tsunami and its penetration into the Lower Columbia River became the subject of “the Workshop on Tsunami Hydrodynamics in a Large River” held in Corvallis, Oregon, 2011. We found that tsunami penetration into the Columbia River is quite different from a typical river. The tsunami enters the vast river estuary through the relatively narrow river mouth of the Columbia, which damps and diffuses its energy. The tsunami transforms into a long period, small amplitude wave that advances to Portland, 173 km from the ocean. Understanding this unique tsunami behavior is important for preparing a forthcoming Cascadia tsunami event. Title: Tsunami Hydrodynamics in the Columbia River Author: Yeh, Harry, Tolkova, Elena, Jay, David A., Talke, Stefan A., Fritz, Hermann Year: 2012 On 11 March 2011, the Tohoku Tsunami overtopped a weir and penetrated 49 km up the Kitakami River, the fourth largest river in Japan. Similarly, the 2010 Chile tsunami propagated at least 15 km up the Maule River. In the Pacific Northwest of the United States, large tsunamis have occurred along the Cascadia subduction zone, most recently the 'orphan tsunami' of 1700 (Atwater et al.). The expected future occurrence of a Cascadia tsunami and its penetration into the Lower Columbia River became the subject of “the Workshop on Tsunami Hydrodynamics in a Large River” held in Corvallis, Oregon, 2011. We found that tsunami penetration into the Columbia River is quite different from a typical river. The tsunami enters the vast river estuary through the relatively narrow river mouth of the Columbia, which damps and diffuses its energy. The tsunami transforms into a long period, small amplitude wave that advances to Portland, 173 km from the ocean. Understanding this unique tsunami behavior is important for preparing a forthcoming Cascadia tsunami event. Close

• 29. [Article] Re and Os isotopes of the central Oregon Cascades and along the arc indicate variable homogenization and mafic growth in the deep crust

  This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/.

  Citation × Citation Citation Abstract Copy Title: Re and Os isotopes of the central Oregon Cascades and along the arc indicate variable homogenization and mafic growth in the deep crust Author: Chesley, John T., Schmidt, Mariek E., Grunder, Anita L., Rowe, Michael C. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/. Title: Re and Os isotopes of the central Oregon Cascades and along the arc indicate variable homogenization and mafic growth in the deep crust Author: Chesley, John T., Schmidt, Mariek E., Grunder, Anita L., Rowe, Michael C. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/. Close

• 30. [Article] Spatially limited mud turbidites on the Cascadia margin: segmented earthquake ruptures?

  This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/.

  Citation × Citation Citation Abstract Copy Title: Spatially limited mud turbidites on the Cascadia margin: segmented earthquake ruptures? Author: Black, B., Goldfinger, C., Patton, J., Beeson, J., Nelson, C. H., Morey, A. E. This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/. Title: Spatially limited mud turbidites on the Cascadia margin: segmented earthquake ruptures? Author: Black, B., Goldfinger, C., Patton, J., Beeson, J., Nelson, C. H., Morey, A. E. This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/. Close

• 31. [Article] Heat flow along the NanTroSEIZE transect: Results from IODP Expeditions 315 and 316 offshore the Kii Peninsula, Japan

  [1] We report detailed thermal measurements undertaken during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316 along the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) transect offshore ...

  Citation × Citation Citation Abstract Copy Title: Heat flow along the NanTroSEIZE transect: Results from IODP Expeditions 315 and 316 offshore the Kii Peninsula, Japan Author: Schmidt‐Schierhorn, Friederike, Spinelli, Glenn, Harris, Robert N. [1] We report detailed thermal measurements undertaken during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316 along the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) transect offshore the Kii Peninsula, Japan. Geothermal objectives included determining thermophysical rock properties of the cored material and characterizing the background thermal regime along this transect. New thermal conductivity measurements made with a divided bar are reported and supplement shipboard full‐ and half‐space thermal conductivity measurements for a total of 938 thermal conductivity measurements. Thermal conductivity varies between about 1.0 W m⁻¹ K⁻¹ near the seafloor to 1.6 W m⁻¹ K⁻¹ at a depth of 1 km. Thermal conductivity generally increases with depth and correlates with variations in porosity and lithology. Thermal gradients along the transect are characterized by 48 sediment temperature measurements from 6 sites. Thermal corrections for the effects of bathymetric relief and sedimentation improve the confidence with which the heat flow values can be interpreted. Heat flow generally decreases with landward distance from the deformation front and varies from 70 mW m⁻² just landward of the deformation front to 54 mW m⁻² at sites characterizing the outer fore‐arc high and to 57 mW m⁻² at the Kumano Basin Site. IODP heat flow measurements are significantly lower than nearby seafloor heat flow measurements. This difference is most likely due to variations in bottom water temperature that have a large effect on values of seafloor heat flow. Thus the heat flow of the Nankai accretionary prism is lower than previously thought. We present thermal models of subduction along this transect and explore the impact of the initial geotherm. Conductive plate cooling based on the age of subducting seafloor (20 Myr) under predicts the observed heat flow. We find a good fit to the data using a geotherm appropriate for 10 Myr seafloor. The extra heat is interpreted in terms of back‐arc thermal environments. Title: Heat flow along the NanTroSEIZE transect: Results from IODP Expeditions 315 and 316 offshore the Kii Peninsula, Japan Author: Schmidt‐Schierhorn, Friederike, Spinelli, Glenn, Harris, Robert N. [1] We report detailed thermal measurements undertaken during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316 along the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) transect offshore the Kii Peninsula, Japan. Geothermal objectives included determining thermophysical rock properties of the cored material and characterizing the background thermal regime along this transect. New thermal conductivity measurements made with a divided bar are reported and supplement shipboard full‐ and half‐space thermal conductivity measurements for a total of 938 thermal conductivity measurements. Thermal conductivity varies between about 1.0 W m⁻¹ K⁻¹ near the seafloor to 1.6 W m⁻¹ K⁻¹ at a depth of 1 km. Thermal conductivity generally increases with depth and correlates with variations in porosity and lithology. Thermal gradients along the transect are characterized by 48 sediment temperature measurements from 6 sites. Thermal corrections for the effects of bathymetric relief and sedimentation improve the confidence with which the heat flow values can be interpreted. Heat flow generally decreases with landward distance from the deformation front and varies from 70 mW m⁻² just landward of the deformation front to 54 mW m⁻² at sites characterizing the outer fore‐arc high and to 57 mW m⁻² at the Kumano Basin Site. IODP heat flow measurements are significantly lower than nearby seafloor heat flow measurements. This difference is most likely due to variations in bottom water temperature that have a large effect on values of seafloor heat flow. Thus the heat flow of the Nankai accretionary prism is lower than previously thought. We present thermal models of subduction along this transect and explore the impact of the initial geotherm. Conductive plate cooling based on the age of subducting seafloor (20 Myr) under predicts the observed heat flow. We find a good fit to the data using a geotherm appropriate for 10 Myr seafloor. The extra heat is interpreted in terms of back‐arc thermal environments. Close

• 32. [Article] Subducted seamounts and recent earthquakes beneath the central Cascadia forearc

  This is the publisher’s final pdf. The published article is copyrighted by Geological Society of America and can be found at: www.geosociety.org/.

  Citation × Citation Citation Abstract Copy Title: Subducted seamounts and recent earthquakes beneath the central Cascadia forearc Author: Blakely, Richard J., Williams, Mark C., Tréhu, Anne M. This is the publisher’s final pdf. The published article is copyrighted by Geological Society of America and can be found at: www.geosociety.org/. Title: Subducted seamounts and recent earthquakes beneath the central Cascadia forearc Author: Blakely, Richard J., Williams, Mark C., Tréhu, Anne M. This is the publisher’s final pdf. The published article is copyrighted by Geological Society of America and can be found at: www.geosociety.org/. Close

• 33. [Article] Mesoscale biogeochemical responses to iron fertilization in the upper layers of the Southern Ocean Iron Experiment areas

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/.

  Citation × Citation Citation Abstract Copy Title: Mesoscale biogeochemical responses to iron fertilization in the upper layers of the Southern Ocean Iron Experiment areas Author: Takahashi, Taro, Hales, Burke This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/. Title: Mesoscale biogeochemical responses to iron fertilization in the upper layers of the Southern Ocean Iron Experiment areas Author: Takahashi, Taro, Hales, Burke This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/. Close

• 34. [Article] Earthquake Relocation in Three-Dimensional Velocity Models for Central Cascadia Continental Margin

  2017

  Citation × Citation Citation Abstract Copy Title: Earthquake Relocation in Three-Dimensional Velocity Models for Central Cascadia Continental Margin Author: Ghorbani, Paria 2017 Title: Earthquake Relocation in Three-Dimensional Velocity Models for Central Cascadia Continental Margin Author: Ghorbani, Paria 2017 Close

• 35. [Article] Simulated tsunami inundation for a range of Cascadia megathrust earthquake scenarios at Bandon, Oregon, USA

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological ...

  Citation × Citation Citation Abstract Copy Title: Simulated tsunami inundation for a range of Cascadia megathrust earthquake scenarios at Bandon, Oregon, USA Author: Priest, George R., Goldfinger, Chris, English, John T., Ferro, Paul A., Witter, Robert C., Wang, Kelin, Zhang, Yinglong J., Stimely, Laura To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological Society of America and can be found at: http://geosphere.geoscienceworld.org/. Title: Simulated tsunami inundation for a range of Cascadia megathrust earthquake scenarios at Bandon, Oregon, USA Author: Priest, George R., Goldfinger, Chris, English, John T., Ferro, Paul A., Witter, Robert C., Wang, Kelin, Zhang, Yinglong J., Stimely, Laura To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological Society of America and can be found at: http://geosphere.geoscienceworld.org/. Close

• 36. [Article] Prolonged plume volcanism in the Caribbean Large Igneous Province: New insights from Curaçao and Haiti

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/.

  Citation × Citation Citation Abstract Copy Title: Prolonged plume volcanism in the Caribbean Large Igneous Province: New insights from Curaçao and Haiti Author: Krawl, Kyle, Kent, Adam J. R., Duncan, Robert A., Loewen, Matthew W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/. Title: Prolonged plume volcanism in the Caribbean Large Igneous Province: New insights from Curaçao and Haiti Author: Krawl, Kyle, Kent, Adam J. R., Duncan, Robert A., Loewen, Matthew W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/. Close

• 37. [Article] A seasonally modulated earthquake swarm near Maupin, Oregon

  This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Oxford University Press on behalf of The Royal Astronomical Society. The published article can ...

  Citation × Citation Citation Abstract Copy Title: A seasonally modulated earthquake swarm near Maupin, Oregon Author: Braunmiller, Jochen, Tréhu, Anne M., Nábělek, John L. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Oxford University Press on behalf of The Royal Astronomical Society. The published article can be found at: http://gji.oxfordjournals.org/. Title: A seasonally modulated earthquake swarm near Maupin, Oregon Author: Braunmiller, Jochen, Tréhu, Anne M., Nábělek, John L. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Oxford University Press on behalf of The Royal Astronomical Society. The published article can be found at: http://gji.oxfordjournals.org/. Close

• 38. [Article] Marine cold seeps and their manifestations: geological control, biogeochemical criteria and environmental conditions

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/531

  Citation × Citation Citation Abstract Copy Title: Marine cold seeps and their manifestations: geological control, biogeochemical criteria and environmental conditions Author: Suess, Erwin This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/531 Title: Marine cold seeps and their manifestations: geological control, biogeochemical criteria and environmental conditions Author: Suess, Erwin This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/531 Close

• 39. [Article] Morphodynamics of prograding beaches: A synthesis of seasonal- to century-scale observations of the Columbia River littoral cell

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier ...

  Citation × Citation Citation Abstract Copy Title: Morphodynamics of prograding beaches: A synthesis of seasonal- to century-scale observations of the Columbia River littoral cell Author: Ruggiero, Peter, Cohn, Nicholas, Gelfenbaum, Guy, Kaminsky, George M. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/marine-geology/ Title: Morphodynamics of prograding beaches: A synthesis of seasonal- to century-scale observations of the Columbia River littoral cell Author: Ruggiero, Peter, Cohn, Nicholas, Gelfenbaum, Guy, Kaminsky, George M. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/marine-geology/ Close

• 40. [Article] Deep electrical resistivity structure of the Northwestern U. S. derived from 3-D inversion of USArray Magnetotelluric data

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/earth-and-planet...

  Citation × Citation Citation Abstract Copy Title: Deep electrical resistivity structure of the Northwestern U. S. derived from 3-D inversion of USArray Magnetotelluric data Author: Kelbert, Anna, Egbert, Gary D., Schultz, Adam, Wannamaker, Philip E., Meqbel, Naser M. This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/earth-and-planetary-science-letters/ Title: Deep electrical resistivity structure of the Northwestern U. S. derived from 3-D inversion of USArray Magnetotelluric data Author: Kelbert, Anna, Egbert, Gary D., Schultz, Adam, Wannamaker, Philip E., Meqbel, Naser M. This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/earth-and-planetary-science-letters/ Close

• 41. [Article] Thermal effects of hydrothermal circulation and seamount subduction: Temperatures in the Nankai Trough Seismogenic Zone Experiment transect, Japan

  This is the publisher's version of record. The original submission is copyrighted by American Geophysical Union and can be found here: http://www.agu.org/

  Citation × Citation Citation Abstract Copy Title: Thermal effects of hydrothermal circulation and seamount subduction: Temperatures in the Nankai Trough Seismogenic Zone Experiment transect, Japan Author: Harris, R. N., Spinelli, G. A. This is the publisher's version of record. The original submission is copyrighted by American Geophysical Union and can be found here: http://www.agu.org/ Title: Thermal effects of hydrothermal circulation and seamount subduction: Temperatures in the Nankai Trough Seismogenic Zone Experiment transect, Japan Author: Harris, R. N., Spinelli, G. A. This is the publisher's version of record. The original submission is copyrighted by American Geophysical Union and can be found here: http://www.agu.org/ Close

• 42. [Article] A seismic reflection profile across the Cascadia subduction zone offshore central Oregon: New constraints on methane distribution and crystal structure

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: A seismic reflection profile across the Cascadia subduction zone offshore central Oregon: New constraints on methane distribution and crystal structure Author: Lin, Guibiao, Goldfinger, Chris, Tréhu, Anne Martine, Maxwell, Edward Copyrighted by American Geophysical Union. Title: A seismic reflection profile across the Cascadia subduction zone offshore central Oregon: New constraints on methane distribution and crystal structure Author: Lin, Guibiao, Goldfinger, Chris, Tréhu, Anne Martine, Maxwell, Edward Copyrighted by American Geophysical Union. Close

• 43. [Article] Age systematics of two young en echelon Samoan volcanic trails

  The volcanic origin of the Samoan archipelago can be explained by one of three models, specifically, by a hot spot forming over a mantle plume, by lithospheric extension resulting from complex subduction ...

  Citation × Citation Citation Abstract Copy Title: Age systematics of two young en echelon Samoan volcanic trails Author: Staudigel, Hubert, Hart, Stanley R., Koppers, Anthony A. P., Jackson, Matthew G., Russell, Jamie A., Wright, Dawn J., Roberts, Jed, Konter, Jasper G. The volcanic origin of the Samoan archipelago can be explained by one of three models, specifically, by a hot spot forming over a mantle plume, by lithospheric extension resulting from complex subduction tectonics in the region, or by a combination of these two processes, either acting sequentially or synchronously. In this paper, we present results of 36 high-resolution ⁴⁰Ar/³⁹Ar incremental heating age analyses for the initial (submarine) phase of Samoan volcanoes, ranging from 13.2 Ma for the westernmost Samoan seamounts to 0.27 Ma in the eastern Samoan volcanic province. Taken as a whole, our new age data point to a hot spot origin for the shield-building volcanism in the Samoan lineament, whereby seamounts younger than 5 Ma are consistent with a model of constant 7.1 cm/yr plate motion, analogous to GPS measurements for the Pacific Plate in this region. This makes our new ⁴⁰Ar/³⁹Ar ages of the submarine basalts all older compared to recent absolute plate motion (APM) models by Wessel et al. (2008), which are based on the inversion of twelve independent seamount trails in the Pacific relative to a fixed reference frame of hot spots and which predict faster plate motions of around 9.3 cm/yr in the vicinity of Samoa. The Samoan ages are also older than APM models by Steinberger et al. (2004) taking into account the motion of hot spots in the Pacific alone or globally. The age systematics become more complicated toward the younger end of the Samoan seamount trail, where its morphology bifurcates into two en echelon subtracks, termed the VAI and MALU trends, as they emanate from two eruptive centers at Vailulu'u and Malumalu seamount, respectively. Spaced ~50 km apart, the VAI and MALU trends have distinct geochemical characters and independent but overlapping linear ⁴⁰Ar/³⁹Ar age progressions since 1.5 Ma. These phenomena are not unique to Samoa, as they have been observed at the Hawaiian hot spot, and can be attributed to a geochemical zoning in its underlying mantle source or plume. Moreover, the processes allowing for the emergence of two distinct eruptive centers in the Samoan archipelago, the stepped offset of these subtracks, and their slight obliqueness with respect to the overall seamount trail orientation may very well be controlled by local tectonics, stresses, and extension, also causing the rejuvenated volcanism on the main islands of Savai'i, Upolu, and Tutuila since 0.4 Ma. Title: Age systematics of two young en echelon Samoan volcanic trails Author: Staudigel, Hubert, Hart, Stanley R., Koppers, Anthony A. P., Jackson, Matthew G., Russell, Jamie A., Wright, Dawn J., Roberts, Jed, Konter, Jasper G. The volcanic origin of the Samoan archipelago can be explained by one of three models, specifically, by a hot spot forming over a mantle plume, by lithospheric extension resulting from complex subduction tectonics in the region, or by a combination of these two processes, either acting sequentially or synchronously. In this paper, we present results of 36 high-resolution ⁴⁰Ar/³⁹Ar incremental heating age analyses for the initial (submarine) phase of Samoan volcanoes, ranging from 13.2 Ma for the westernmost Samoan seamounts to 0.27 Ma in the eastern Samoan volcanic province. Taken as a whole, our new age data point to a hot spot origin for the shield-building volcanism in the Samoan lineament, whereby seamounts younger than 5 Ma are consistent with a model of constant 7.1 cm/yr plate motion, analogous to GPS measurements for the Pacific Plate in this region. This makes our new ⁴⁰Ar/³⁹Ar ages of the submarine basalts all older compared to recent absolute plate motion (APM) models by Wessel et al. (2008), which are based on the inversion of twelve independent seamount trails in the Pacific relative to a fixed reference frame of hot spots and which predict faster plate motions of around 9.3 cm/yr in the vicinity of Samoa. The Samoan ages are also older than APM models by Steinberger et al. (2004) taking into account the motion of hot spots in the Pacific alone or globally. The age systematics become more complicated toward the younger end of the Samoan seamount trail, where its morphology bifurcates into two en echelon subtracks, termed the VAI and MALU trends, as they emanate from two eruptive centers at Vailulu'u and Malumalu seamount, respectively. Spaced ~50 km apart, the VAI and MALU trends have distinct geochemical characters and independent but overlapping linear ⁴⁰Ar/³⁹Ar age progressions since 1.5 Ma. These phenomena are not unique to Samoa, as they have been observed at the Hawaiian hot spot, and can be attributed to a geochemical zoning in its underlying mantle source or plume. Moreover, the processes allowing for the emergence of two distinct eruptive centers in the Samoan archipelago, the stepped offset of these subtracks, and their slight obliqueness with respect to the overall seamount trail orientation may very well be controlled by local tectonics, stresses, and extension, also causing the rejuvenated volcanism on the main islands of Savai'i, Upolu, and Tutuila since 0.4 Ma. Close

• 44. [Article] GPS-determination of along-strike variation in Cascadia margin kinematics: Implications for relative plate motion, subduction zone coupling, and permanent deformation

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: GPS-determination of along-strike variation in Cascadia margin kinematics: Implications for relative plate motion, subduction zone coupling, and permanent deformation Author: Goldfinger, Chris, Johnson, Daniel J., Dragert, Herb, Rubin, Charles M., Miller, M. Meghan, Qamar, Anthony, Wang, Kelin Copyrighted by American Geophysical Union. Title: GPS-determination of along-strike variation in Cascadia margin kinematics: Implications for relative plate motion, subduction zone coupling, and permanent deformation Author: Goldfinger, Chris, Johnson, Daniel J., Dragert, Herb, Rubin, Charles M., Miller, M. Meghan, Qamar, Anthony, Wang, Kelin Copyrighted by American Geophysical Union. Close

• 45. [Article] Temporal variation of methane flares in the ocean above Hydrate Ridge, Oregon

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/earth-and-planet...

  Citation × Citation Citation Abstract Copy Title: Temporal variation of methane flares in the ocean above Hydrate Ridge, Oregon Author: Caress, David W., Kannberg, Peter K., Pierce, Stephen D, Paull, Charles K, Tréhu, Anne This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/earth-and-planetary-science-letters/. Title: Temporal variation of methane flares in the ocean above Hydrate Ridge, Oregon Author: Caress, David W., Kannberg, Peter K., Pierce, Stephen D, Paull, Charles K, Tréhu, Anne This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/earth-and-planetary-science-letters/. Close

• 46. [Article] Two coastal upwelling domains in the northern California Current system

  A pair of hydrographic sections, one north and one south of Cape Blanco at 42.9N, was sampled in five summers (1998–2000 and 2002–2003). The NH line at 44.6N lies about 130 km south of the Columbia River, ...

  Citation × Citation Citation Abstract Copy Title: Two coastal upwelling domains in the northern California Current system Author: Wheeler, Patricia A., Smith, Robert L. (Robert Lloyd), 1935-, Perlin, Natalie, Keister, Julie Eileen, Huyer, Adriana, 1945-, Kosro, P. Michael, 1951-, Fleischbein, Jane A pair of hydrographic sections, one north and one south of Cape Blanco at 42.9N, was sampled in five summers (1998–2000 and 2002–2003). The NH line at 44.6N lies about 130 km south of the Columbia River, and spans a relatively wide shelf off Newport, Oregon. The CR line at 41.9N off Crescent City, California, lies 300 km farther south and spans a narrower shelf. Summer winds are predominantly southward in both locations but the southward winds are stronger on the CR line. Sampling included CTD/rosette casts (to measure temperature, salinity, dissolved oxygen, nutrients, chlorophyll), zooplankton net tows and continuous operation of an Acoustic Doppler Current Profiler. We summarize and compare July-August observations from the two locations. We find significant summer-season differences in the coastal upwelling domains north and south of Cape Blanco. Compared to the domain off Newport, the domain off Crescent City has a more saline, cooler, denser and thicker surface mixed layer, a wider coastal zone inshore of the upwelling front and jet, higher nutrient concentrations in the photic zone and higher phytoplankton biomass. The southward coastal jet lies near the coast (about 20–30 km offshore, over the shelf) on the NH line, but far from shore (about 120 km) on the CR line; a weak secondary jet lies near the shelf-break (35 km from shore) off Crescent City. Phytoplankton tend to be light-limited on the CR line and nutrient-limited on the NH line. Copepod biomass is high (15 mg C m-3) inshore of the mid-shelf on both NH and CR lines, and is also high in the core of the coastal jet off Crescent City. The CR line shows evidence of deep chlorophyll pockets that have been subducted from the surface layer. We attribute these significant differences to stronger mean southward wind stress over the southern domain, to strong small-scale wind stress curl in the lee of Cape Blanco, and to the reduced influence of the Columbia River discharge in this region. Title: Two coastal upwelling domains in the northern California Current system Author: Wheeler, Patricia A., Smith, Robert L. (Robert Lloyd), 1935-, Perlin, Natalie, Keister, Julie Eileen, Huyer, Adriana, 1945-, Kosro, P. Michael, 1951-, Fleischbein, Jane A pair of hydrographic sections, one north and one south of Cape Blanco at 42.9N, was sampled in five summers (1998–2000 and 2002–2003). The NH line at 44.6N lies about 130 km south of the Columbia River, and spans a relatively wide shelf off Newport, Oregon. The CR line at 41.9N off Crescent City, California, lies 300 km farther south and spans a narrower shelf. Summer winds are predominantly southward in both locations but the southward winds are stronger on the CR line. Sampling included CTD/rosette casts (to measure temperature, salinity, dissolved oxygen, nutrients, chlorophyll), zooplankton net tows and continuous operation of an Acoustic Doppler Current Profiler. We summarize and compare July-August observations from the two locations. We find significant summer-season differences in the coastal upwelling domains north and south of Cape Blanco. Compared to the domain off Newport, the domain off Crescent City has a more saline, cooler, denser and thicker surface mixed layer, a wider coastal zone inshore of the upwelling front and jet, higher nutrient concentrations in the photic zone and higher phytoplankton biomass. The southward coastal jet lies near the coast (about 20–30 km offshore, over the shelf) on the NH line, but far from shore (about 120 km) on the CR line; a weak secondary jet lies near the shelf-break (35 km from shore) off Crescent City. Phytoplankton tend to be light-limited on the CR line and nutrient-limited on the NH line. Copepod biomass is high (15 mg C m-3) inshore of the mid-shelf on both NH and CR lines, and is also high in the core of the coastal jet off Crescent City. The CR line shows evidence of deep chlorophyll pockets that have been subducted from the surface layer. We attribute these significant differences to stronger mean southward wind stress over the southern domain, to strong small-scale wind stress curl in the lee of Cape Blanco, and to the reduced influence of the Columbia River discharge in this region. Close

• 47. [Article] Magnetotelluric observations across the Juan de Fuca subduction system in the EMSLAB project

  A magnetotelluric (MT)transect has been obtained near latitude 45øN from the active Juan de Fuca Spreading center, across the subduction zone and Cascades volcanic arc, and into the back arc Deschutes Basin ...

  Citation × Citation Citation Abstract Copy Title: Magnetotelluric observations across the Juan de Fuca subduction system in the EMSLAB project Author: Segawa, Jiro S., Tarits, Pascal, Yukutake, Takesi, Chave, Alan D., Booker, John R., Filloux, Jean H., Egbert, Gary D., Stodt, John A., Martinez, Mario G., Jiracek, George R., Jones, Alan G., Law, Lawrie K., Waff, Harve S., Wannamaker, Philip E., Green, A.W., Young, Charles T., White, Anthony A magnetotelluric (MT)transect has been obtained near latitude 45øN from the active Juan de Fuca Spreading center, across the subduction zone and Cascades volcanic arc, and into the back arc Deschutes Basin region. This paper presents the MT data set and describes its major characteristics as they pertain to the resistivity of the subduction system. In addition, we discuss the measurement and processing procedures employed as well as important concerns in data interpretation. Broadband audiomagnetotelluric (AMT)/MT soundings( approx. 0.01-500 s period) were collected on land with considerable redundancy in site location, and from which 39 sites were selected which constrain upper crustal heterogeneity but sense also into the upper mantle. Fifteen long-period MT recordings (about 50-10,000 s) on land confirm the broadband responses in their common period range and extend the depths of exploration to hundreds of kilometers. On the Juan de Fuca plate offshore, 33 out of 39 sea floor instruments at 19 locations gave good results. Of these locations, five magnetotelluric soundings plus two additional geomagnetic variation sites, covering the period range 200-10^(5) s approximately, constitute the ocean bottom segment of our profile. The feature of the land observations which probably relates most closely to the subduction process is a peak in the impedance phase of the transverse magnetic mode around 30-50 s period. This phase anomaly, with a corresponding inflection in the apparent resistivity, is continuous eastward from the seacoast and ends abruptly at the High Cascades. It signifies an electrically conductive layer in otherwise resistive lower crust or upper mantle, with the layer conductance decreasing eastward from the coast to a minimum under the Coast Range but increasing suddenly to the east of the central Willamette Basin. The higher conductance to the east is corroborated by the vertical magnetic field transfer function whose real component shows negative values in the period range 100-1000 s over the same distance. The transverse electric mode apparent resistivity and phase on the land display a variety of three-dimensional effects which make their interpretation difficult. Conversely, both modes of the ocean floor soundings exhibit a smooth progression laterally from the coastal area to the spreading ridge, indicating that the measurements here are reflecting primarily the large-scale tectonic structures of interest and are little disturbed by small near-surface inhomogeneities. The impedance data near the ridge are strongly suggestive of a low-resistivity asthenosphere beneath resistive Juan de Fuca plate lithosphere. Approaching the coastline to the east, both impedance and vertical magnetic field responses appear increasingly affected by a thick wedge of deposited and accreted sediments and by the thinning of the seawater. Title: Magnetotelluric observations across the Juan de Fuca subduction system in the EMSLAB project Author: Segawa, Jiro S., Tarits, Pascal, Yukutake, Takesi, Chave, Alan D., Booker, John R., Filloux, Jean H., Egbert, Gary D., Stodt, John A., Martinez, Mario G., Jiracek, George R., Jones, Alan G., Law, Lawrie K., Waff, Harve S., Wannamaker, Philip E., Green, A.W., Young, Charles T., White, Anthony A magnetotelluric (MT)transect has been obtained near latitude 45øN from the active Juan de Fuca Spreading center, across the subduction zone and Cascades volcanic arc, and into the back arc Deschutes Basin region. This paper presents the MT data set and describes its major characteristics as they pertain to the resistivity of the subduction system. In addition, we discuss the measurement and processing procedures employed as well as important concerns in data interpretation. Broadband audiomagnetotelluric (AMT)/MT soundings( approx. 0.01-500 s period) were collected on land with considerable redundancy in site location, and from which 39 sites were selected which constrain upper crustal heterogeneity but sense also into the upper mantle. Fifteen long-period MT recordings (about 50-10,000 s) on land confirm the broadband responses in their common period range and extend the depths of exploration to hundreds of kilometers. On the Juan de Fuca plate offshore, 33 out of 39 sea floor instruments at 19 locations gave good results. Of these locations, five magnetotelluric soundings plus two additional geomagnetic variation sites, covering the period range 200-10^(5) s approximately, constitute the ocean bottom segment of our profile. The feature of the land observations which probably relates most closely to the subduction process is a peak in the impedance phase of the transverse magnetic mode around 30-50 s period. This phase anomaly, with a corresponding inflection in the apparent resistivity, is continuous eastward from the seacoast and ends abruptly at the High Cascades. It signifies an electrically conductive layer in otherwise resistive lower crust or upper mantle, with the layer conductance decreasing eastward from the coast to a minimum under the Coast Range but increasing suddenly to the east of the central Willamette Basin. The higher conductance to the east is corroborated by the vertical magnetic field transfer function whose real component shows negative values in the period range 100-1000 s over the same distance. The transverse electric mode apparent resistivity and phase on the land display a variety of three-dimensional effects which make their interpretation difficult. Conversely, both modes of the ocean floor soundings exhibit a smooth progression laterally from the coastal area to the spreading ridge, indicating that the measurements here are reflecting primarily the large-scale tectonic structures of interest and are little disturbed by small near-surface inhomogeneities. The impedance data near the ridge are strongly suggestive of a low-resistivity asthenosphere beneath resistive Juan de Fuca plate lithosphere. Approaching the coastline to the east, both impedance and vertical magnetic field responses appear increasingly affected by a thick wedge of deposited and accreted sediments and by the thinning of the seawater. Close

• 48. [Article] Water mass subduction and the transport of phytoplankton in a coastal upwelling system

  Observations during the Coastal Transition Zone (CTZ) experiment in summer 1988 reveal the presence of deep phytoplankton layers in a coastal upwelling system. The layers occur throughout the CTZ study ...

  Citation × Citation Citation Abstract Copy Title: Water mass subduction and the transport of phytoplankton in a coastal upwelling system Author: Washburn, Libe, Hayward, Thomas, Kadko, David C., Ramp, Steve, Cowles, Timothy, Kosro, P. Michael, 1951-, Stanton, Timothy P., Jones, Burton H. Observations during the Coastal Transition Zone (CTZ) experiment in summer 1988 reveal the presence of deep phytoplankton layers in a coastal upwelling system. The layers occur throughout the CTZ study area, including a strong baroclinic jet which was present over the period of the experiment. On the basis of a variety of bio-optical, hydrographic, and geochemical indicators, it is concluded that the water masses associated with the layers result from subduction processes. Criteria are developed for identification of subducted water masses based on the beam attenuation coefficient, chlorophyll fluorescence, and distribution of light in the water column. Temperature-salinity characteristics are consistent with two source regions for the subducted layers, one nearshore and a second farther offshore. Most of the layers correspond to the inshore source which is apparently distributed alongshore. Subducted water masses are found in all six grid surveys of the CTZ experiment and probably result from a variety of physical processes. One of these is flow along sloping isopycnal surfaces due to advection and mixing processes. Advection time scales for flow out the axis of the jet range from a few days to a few weeks, depending on the depth of a particular surface, and the bio-optical indicators for subduction processes persist over these time scales Title: Water mass subduction and the transport of phytoplankton in a coastal upwelling system Author: Washburn, Libe, Hayward, Thomas, Kadko, David C., Ramp, Steve, Cowles, Timothy, Kosro, P. Michael, 1951-, Stanton, Timothy P., Jones, Burton H. Observations during the Coastal Transition Zone (CTZ) experiment in summer 1988 reveal the presence of deep phytoplankton layers in a coastal upwelling system. The layers occur throughout the CTZ study area, including a strong baroclinic jet which was present over the period of the experiment. On the basis of a variety of bio-optical, hydrographic, and geochemical indicators, it is concluded that the water masses associated with the layers result from subduction processes. Criteria are developed for identification of subducted water masses based on the beam attenuation coefficient, chlorophyll fluorescence, and distribution of light in the water column. Temperature-salinity characteristics are consistent with two source regions for the subducted layers, one nearshore and a second farther offshore. Most of the layers correspond to the inshore source which is apparently distributed alongshore. Subducted water masses are found in all six grid surveys of the CTZ experiment and probably result from a variety of physical processes. One of these is flow along sloping isopycnal surfaces due to advection and mixing processes. Advection time scales for flow out the axis of the jet range from a few days to a few weeks, depending on the depth of a particular surface, and the bio-optical indicators for subduction processes persist over these time scales Close

• 49. [Article] Age constraints on crustal recycling to the mantle beneath the southern Chile Ridge: He-Pb-Sr-Nd isotope systematics

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Age constraints on crustal recycling to the mantle beneath the southern Chile Ridge: He-Pb-Sr-Nd isotope systematics Author: Klein, Emily M., Sturm, Marnie E., Graham, David W., Karsten, Jill Copyrighted by American Geophysical Union. Title: Age constraints on crustal recycling to the mantle beneath the southern Chile Ridge: He-Pb-Sr-Nd isotope systematics Author: Klein, Emily M., Sturm, Marnie E., Graham, David W., Karsten, Jill Copyrighted by American Geophysical Union. Close

• 50. [Article] Feeding methane vents and gas hydrate deposits at south Hydrate Ridge

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Feeding methane vents and gas hydrate deposits at south Hydrate Ridge Author: Torres, Marta E., Liu, Xiaoli, Riedel, Michael, Bangs, Nathan Lawrence Bailey, Johnson, Joel E., Tréhu, Anne Martine, Flemings, Peter B., Gracia, Eulalia, Liu, C. S., Chevallier, Johanna Copyrighted by American Geophysical Union. Title: Feeding methane vents and gas hydrate deposits at south Hydrate Ridge Author: Torres, Marta E., Liu, Xiaoli, Riedel, Michael, Bangs, Nathan Lawrence Bailey, Johnson, Joel E., Tréhu, Anne Martine, Flemings, Peter B., Gracia, Eulalia, Liu, C. S., Chevallier, Johanna Copyrighted by American Geophysical Union. Close

• 51. [Article] Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones

  This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html.

  Citation × Citation Citation Abstract Copy Title: Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones Author: Patton, J. R., Udrekh, Goldfinger, C., Djadjadihardja, Y., Morey, A. E., Romsos, C., Black, B. This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html. Title: Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones Author: Patton, J. R., Udrekh, Goldfinger, C., Djadjadihardja, Y., Morey, A. E., Romsos, C., Black, B. This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html. Close

• 52. [Article] Sedimentology of Seismo-Turbidites off the Cascadia and Northern California Active Tectonic Continental Margins, Northwest Pacific Ocean

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/marine-geology/....

  Citation × Citation Citation Abstract Copy Title: Sedimentology of Seismo-Turbidites off the Cascadia and Northern California Active Tectonic Continental Margins, Northwest Pacific Ocean Author: Gutierrez-Pastor, Julia, Escutia, Carlota, Nelson, C. Hans, Goldfinger, Chris This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/marine-geology/. Title: Sedimentology of Seismo-Turbidites off the Cascadia and Northern California Active Tectonic Continental Margins, Northwest Pacific Ocean Author: Gutierrez-Pastor, Julia, Escutia, Carlota, Nelson, C. Hans, Goldfinger, Chris This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/marine-geology/. Close

• 53. [Article] Phytoplankton and photosynthetic light response in the coastal transition zone off northern California in June 1987

  In June 1987 the geostropic flow in the coastal transition zone off northern California (between 50 and 150 km off the coast from Point Reyes to just north of Cape Mendocino) was dominated by a well-defined, ...

  Citation × Citation Citation Abstract Copy Title: Phytoplankton and photosynthetic light response in the coastal transition zone off northern California in June 1987 Author: Abbott, Mark R., Hood, R. R., Huyer, Adriana, 1945- In June 1987 the geostropic flow in the coastal transition zone off northern California (between 50 and 150 km off the coast from Point Reyes to just north of Cape Mendocino) was dominated by a well-defined, southward-meandering current. Three vertical sections are presented that show the hydrographic structure of the current down to 100 m and its relationship to the distribution of phytoplankton biomass. The sections show that the geostrophic adjustment brought cold, saline, deep water up to the surface on the low steric height, or cold side of the flow, and that this upwelled water supported a relatively large diatom biomass (chlorophyll-a concentrations between 1 and 10 mg m-3). We present particle size spectra and photomicrographs of the phytoplankton that show that the diatom biomass was dominated by chain-forming species (e.g., Skeletonema costatum, Chaetoceros spp., Thalassiosira spp., and Rhizosolenia alata, but also a single-celled Actinocyclus sp.). Photosynthetic light response measurements reveal that these diatom communities were capable of high photosynthetic rates (Pmax between 5 and 25 mg C mg Chla-1 h-1). Although most of the diatoms were located in cold, slow-moving water on the low side of the current, some were being carried downstream. High chlorophyll concentrations were observed at depths > 75 m in and along the cold edge of the flow in all of our sections; we show evidence that in tow out of three cases this was the result of water mass subduction. Title: Phytoplankton and photosynthetic light response in the coastal transition zone off northern California in June 1987 Author: Abbott, Mark R., Hood, R. R., Huyer, Adriana, 1945- In June 1987 the geostropic flow in the coastal transition zone off northern California (between 50 and 150 km off the coast from Point Reyes to just north of Cape Mendocino) was dominated by a well-defined, southward-meandering current. Three vertical sections are presented that show the hydrographic structure of the current down to 100 m and its relationship to the distribution of phytoplankton biomass. The sections show that the geostrophic adjustment brought cold, saline, deep water up to the surface on the low steric height, or cold side of the flow, and that this upwelled water supported a relatively large diatom biomass (chlorophyll-a concentrations between 1 and 10 mg m-3). We present particle size spectra and photomicrographs of the phytoplankton that show that the diatom biomass was dominated by chain-forming species (e.g., Skeletonema costatum, Chaetoceros spp., Thalassiosira spp., and Rhizosolenia alata, but also a single-celled Actinocyclus sp.). Photosynthetic light response measurements reveal that these diatom communities were capable of high photosynthetic rates (Pmax between 5 and 25 mg C mg Chla-1 h-1). Although most of the diatoms were located in cold, slow-moving water on the low side of the current, some were being carried downstream. High chlorophyll concentrations were observed at depths > 75 m in and along the cold edge of the flow in all of our sections; we show evidence that in tow out of three cases this was the result of water mass subduction. Close

• 54. [Article] Relationship of pore water freshening to accretionary processes in the Cascadia margin: Fluid sources and gas hydrate abundance

  Drilling in the Cascadia accretionary complex enable us to evaluate the contribution of dehydration reactions and gas hydrate dissociation to pore water freshening. The observed freshening with depth and ...

  Citation × Citation Citation Abstract Copy Title: Relationship of pore water freshening to accretionary processes in the Cascadia margin: Fluid sources and gas hydrate abundance Author: Torres, Marta E., Tomaru, H., Teichert, B. M. A., Borowski, W., Tréhu, Anne Martine Drilling in the Cascadia accretionary complex enable us to evaluate the contribution of dehydration reactions and gas hydrate dissociation to pore water freshening. The observed freshening with depth and distance from the prism toe is consistent with enhanced conversion of smectite to illite, driven by increase in temperature and age of accreted sediments. Although they contain gas hydrate -as evidenced by discrete low chloride spikes- the westernmost sites drilled on Hydrate Ridge show no freshening trend with depth. Strontium data reveal that all the me´lange samples contain deep fluids modified by reaction with the subducting oceanic crust. Thus we infer that, at the westernmost sites, accretion is too recent for the sediments to have undergone significant illitization. Our data demonstrate that a smooth decrease in dissolved chloride with depth cannot generally be used to infer the presence or to estimate the amount of gas hydrate in accretionary margins. Title: Relationship of pore water freshening to accretionary processes in the Cascadia margin: Fluid sources and gas hydrate abundance Author: Torres, Marta E., Tomaru, H., Teichert, B. M. A., Borowski, W., Tréhu, Anne Martine Drilling in the Cascadia accretionary complex enable us to evaluate the contribution of dehydration reactions and gas hydrate dissociation to pore water freshening. The observed freshening with depth and distance from the prism toe is consistent with enhanced conversion of smectite to illite, driven by increase in temperature and age of accreted sediments. Although they contain gas hydrate -as evidenced by discrete low chloride spikes- the westernmost sites drilled on Hydrate Ridge show no freshening trend with depth. Strontium data reveal that all the me´lange samples contain deep fluids modified by reaction with the subducting oceanic crust. Thus we infer that, at the westernmost sites, accretion is too recent for the sediments to have undergone significant illitization. Our data demonstrate that a smooth decrease in dissolved chloride with depth cannot generally be used to infer the presence or to estimate the amount of gas hydrate in accretionary margins. Close

• 55. [Article] Origin of volcanic seamounts at the continental margin of California related to changes in plate margins

  Volcanic samples collected with the Monterey Bay Aquarium Research Institute's ROV Tiburon from eight seamounts at the continental margin offshore central to southern California comprise a diverse suite ...

  Citation × Citation Citation Abstract Copy Title: Origin of volcanic seamounts at the continental margin of California related to changes in plate margins Author: Davis, A. S., Huard, J., Paduan, J. B., Clague, D. A., Cousens, B. L. Volcanic samples collected with the Monterey Bay Aquarium Research Institute's ROV Tiburon from eight seamounts at the continental margin offshore central to southern California comprise a diverse suite of mainly alkalic basalt to trachyte but also include rare tholeiitic basalt and basanite. All samples experienced complex crystal fractionation probably near the crust/mantle boundary, based on the presence in some of mantle xenoliths. Incompatible trace elements, poorly correlated with isotopic compositions, suggest variable degrees of partial melting of compositionally heterogeneous mantle sources, ranging from MORB-like to relatively enriched OIB. High-precision ⁴⁰Ar/³⁹Ar ages indicate episodes of volcanic activity mainly from 16 to 7 Ma but document one eruption as recent as 2.8 Ma at San Juan Seamount. Synchronous episodes of volcanism occurred at geographically widely separated locations offshore and within the continental borderland. Collectively, the samples from these seamounts have age ranges and chemical compositions similar to those from Davidson Seamount, identified as being located atop an abandoned spreading center. These seamounts appear to have a common origin ultimately related to abandonment and partial subduction of spreading center segments when the plate boundary changed from subduction-dominated to a transform margin. They differ in composition, age, and origin from other more widespread near-ridge seamounts, which commonly have circular plans with nested calderas, and from age progressive volcanoes in linear arrays, such as the Fieberling-Guadalupe chain, that occur in the same region. Each volcanic episode represents decompression melting of discrete enriched material in the suboceanic mantle with melts rising along zones of weakness in the oceanic crust fabric. The process may be aided by transtensional tectonics related to continued faulting along the continental margin. Title: Origin of volcanic seamounts at the continental margin of California related to changes in plate margins Author: Davis, A. S., Huard, J., Paduan, J. B., Clague, D. A., Cousens, B. L. Volcanic samples collected with the Monterey Bay Aquarium Research Institute's ROV Tiburon from eight seamounts at the continental margin offshore central to southern California comprise a diverse suite of mainly alkalic basalt to trachyte but also include rare tholeiitic basalt and basanite. All samples experienced complex crystal fractionation probably near the crust/mantle boundary, based on the presence in some of mantle xenoliths. Incompatible trace elements, poorly correlated with isotopic compositions, suggest variable degrees of partial melting of compositionally heterogeneous mantle sources, ranging from MORB-like to relatively enriched OIB. High-precision ⁴⁰Ar/³⁹Ar ages indicate episodes of volcanic activity mainly from 16 to 7 Ma but document one eruption as recent as 2.8 Ma at San Juan Seamount. Synchronous episodes of volcanism occurred at geographically widely separated locations offshore and within the continental borderland. Collectively, the samples from these seamounts have age ranges and chemical compositions similar to those from Davidson Seamount, identified as being located atop an abandoned spreading center. These seamounts appear to have a common origin ultimately related to abandonment and partial subduction of spreading center segments when the plate boundary changed from subduction-dominated to a transform margin. They differ in composition, age, and origin from other more widespread near-ridge seamounts, which commonly have circular plans with nested calderas, and from age progressive volcanoes in linear arrays, such as the Fieberling-Guadalupe chain, that occur in the same region. Each volcanic episode represents decompression melting of discrete enriched material in the suboceanic mantle with melts rising along zones of weakness in the oceanic crust fabric. The process may be aided by transtensional tectonics related to continued faulting along the continental margin. Close

• 56. [Article] Seismotectonics of the Explorer region

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Seismotectonics of the Explorer region Author: Braunmiller, Jochen, Nábělek, John Copyrighted by American Geophysical Union. Title: Seismotectonics of the Explorer region Author: Braunmiller, Jochen, Nábělek, John Copyrighted by American Geophysical Union. Close

• 57. [Article] Thermal regime of the Costa Rican convergent margin: 2. Thermal models of the shallow Middle America subduction zone offshore Costa Rica

  At the Costa Rica margin along the Middle America Trench along‐strike variations in heat flow are well mapped. These variations can be understood in terms of either ventilated fluid flow, where exposed ...

  Citation × Citation Citation Abstract Copy Title: Thermal regime of the Costa Rican convergent margin: 2. Thermal models of the shallow Middle America subduction zone offshore Costa Rica Author: Ranero, César R., Spinelli, Glenn, Harris, Robert N. At the Costa Rica margin along the Middle America Trench along‐strike variations in heat flow are well mapped. These variations can be understood in terms of either ventilated fluid flow, where exposed basement allows fluids to freely advect heat between the crustal aquifer and ocean, or insulated fluid flow where continuous sediment cover restricts heat advection to within the crustal aquifer. We model fluid flow within the subducting aquifer using Nusselt number approximations coupled with finite element models of subduction and explore its effect on temperatures along the subduction thrust. The sensitivity of these models to the initial thermal state of the plate and styles of fluid flow, either ventilated or insulated, is explored. Heat flow measurements on cool crust accreted at the East Pacific Rise are consistent with ventilated hydrothermal cooling that continues with subduction. These models yield much cooler temperatures than predicted from simulations initialized with conductive predictions and without hydrothermal circulation. Heat flow transects on warm crust accreted at the Cocos‐Nazca spreading center are consistent with models of insulated hydrothermal circulation that advects heat updip within the subducting crustal aquifer. Near the trench these models are warmer than conductive predictions and cooler than conductive predictions downdip of the trench. Comparisons between microseismicity and modeled isotherms suggest that the updip limit of microseismicity occurs at temperatures warmer than 100°C and that the downdip extent of microseismicity is bounded by the intersection of the subduction thrust with the base of the overriding crust. Title: Thermal regime of the Costa Rican convergent margin: 2. Thermal models of the shallow Middle America subduction zone offshore Costa Rica Author: Ranero, César R., Spinelli, Glenn, Harris, Robert N. At the Costa Rica margin along the Middle America Trench along‐strike variations in heat flow are well mapped. These variations can be understood in terms of either ventilated fluid flow, where exposed basement allows fluids to freely advect heat between the crustal aquifer and ocean, or insulated fluid flow where continuous sediment cover restricts heat advection to within the crustal aquifer. We model fluid flow within the subducting aquifer using Nusselt number approximations coupled with finite element models of subduction and explore its effect on temperatures along the subduction thrust. The sensitivity of these models to the initial thermal state of the plate and styles of fluid flow, either ventilated or insulated, is explored. Heat flow measurements on cool crust accreted at the East Pacific Rise are consistent with ventilated hydrothermal cooling that continues with subduction. These models yield much cooler temperatures than predicted from simulations initialized with conductive predictions and without hydrothermal circulation. Heat flow transects on warm crust accreted at the Cocos‐Nazca spreading center are consistent with models of insulated hydrothermal circulation that advects heat updip within the subducting crustal aquifer. Near the trench these models are warmer than conductive predictions and cooler than conductive predictions downdip of the trench. Comparisons between microseismicity and modeled isotherms suggest that the updip limit of microseismicity occurs at temperatures warmer than 100°C and that the downdip extent of microseismicity is bounded by the intersection of the subduction thrust with the base of the overriding crust. Close

• 58. [Article] Tectonically controlled origin of three unusual rock suites in the Woodlark basin

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Tectonically controlled origin of three unusual rock suites in the Woodlark basin Author: Abbott, Dallas, Fisk, Martin R. Copyrighted by American Geophysical Union. Title: Tectonically controlled origin of three unusual rock suites in the Woodlark basin Author: Abbott, Dallas, Fisk, Martin R. Copyrighted by American Geophysical Union. Close

• 59. [Article] Hotspots, mantle plumes, flood basalts, and true polar wander

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Hotspots, mantle plumes, flood basalts, and true polar wander Author: Duncan, Robert A., Richards, M. A. copyrighted by American Geophysical Union Title: Hotspots, mantle plumes, flood basalts, and true polar wander Author: Duncan, Robert A., Richards, M. A. copyrighted by American Geophysical Union Close

• 60. [Article] Elemental and isotopic abundance of noble gases in formation fluids recovered in situ from the Chile Triple Juction

  Sedimentary pore fluids from the Chile Triple Junction were sampled in situ, and analyzed for their noble gas composition. ³He/⁴He and ⁴He/Ne ratios were used to evaluate the fraction of helium in the ...

  Citation × Citation Citation Abstract Copy Title: Elemental and isotopic abundance of noble gases in formation fluids recovered in situ from the Chile Triple Juction Author: Torres, Marta E., Winckler, Gisela, Suckow, Axel, Bayer, Reinhold, Froelich, Philip N. Sedimentary pore fluids from the Chile Triple Junction were sampled in situ, and analyzed for their noble gas composition. ³He/⁴He and ⁴He/Ne ratios were used to evaluate the fraction of helium in the samples that originated from mantle and radiogenic sources. The results show no primordial helium in samples recovered from Sites 860 and 861. In contrast, a primordial component is present in two samples from a depth interval in Site 863 that corresponds to a zone of tectonic discontinuity. A decrease in the concentration of dissolved K, Sr, Mg, and SO₄ in this interval is consistent with the presence of a fluid which has been altered by basalt-seawater reactions. These results indicate lateral fluid migration from a hydrothermal source which is probably associated with the recently subducted Chile Ridge axis. Title: Elemental and isotopic abundance of noble gases in formation fluids recovered in situ from the Chile Triple Juction Author: Torres, Marta E., Winckler, Gisela, Suckow, Axel, Bayer, Reinhold, Froelich, Philip N. Sedimentary pore fluids from the Chile Triple Junction were sampled in situ, and analyzed for their noble gas composition. ³He/⁴He and ⁴He/Ne ratios were used to evaluate the fraction of helium in the samples that originated from mantle and radiogenic sources. The results show no primordial helium in samples recovered from Sites 860 and 861. In contrast, a primordial component is present in two samples from a depth interval in Site 863 that corresponds to a zone of tectonic discontinuity. A decrease in the concentration of dissolved K, Sr, Mg, and SO₄ in this interval is consistent with the presence of a fluid which has been altered by basalt-seawater reactions. These results indicate lateral fluid migration from a hydrothermal source which is probably associated with the recently subducted Chile Ridge axis. Close

• 61. [Article] Geological and geochemical contraints on the isotopic composition of interstitial waters from the Hydrate Ridge region, Cascadia Continental margin

  The isotopic compositions of interstitial waters collected from Hydrate Ridge during Ocean Drilling Program Leg 204 were measured to evaluate the fluid evolution of this accretionary prism. At shallow depths, ...

  Citation × Citation Citation Abstract Copy Title: Geological and geochemical contraints on the isotopic composition of interstitial waters from the Hydrate Ridge region, Cascadia Continental margin Author: Torres, Marta E., Matsumoto, R., Tomaru, A. M., Borowski, Walter S. The isotopic compositions of interstitial waters collected from Hydrate Ridge during Ocean Drilling Program Leg 204 were measured to evaluate the fluid evolution of this accretionary prism. At shallow depths, the dissolved Cl- concentrations and δD and δ¹⁸O values of the interstitial water reflect changes in the salinity and the isotopic compositions of seawater from the Last Glacial Maximum to the present. The presence of disseminated gas hydrates, which is well identified by discrete low Cl- anomalies within the gas hydrate stability zone, is accompanied by high δD and δ¹⁸O values of the freshened fluids. This is consistent with incorporation of heavy isotopes into the gas hydrate lattice, which is also apparent in the signals observed at the ridge summit. Here, massive gas hydrate formation in the upper 20 meters below seafloor leads the formation of brines with dissolved Cl- concentrations as high as 1400 mM. The interstitial waters sampled near massive gas hydrates at the ridge summit are extremely depleted in D and ¹⁸O. Clay mineral dehydration within the deep prism results in a progressive decrease in Cl¯ and δD with depth. Dehydration temperature estimates based on those data likely suggest a progressive increase in the temperature of isotopic fractionation between clay and water with distance from the prism toe. The oxygen isotope data probably reflect the combined effects of clay dehydration, carbonate precipitation, and alteration of oceanic basement; however, there are not enough data to constrain the relative contribution of these processes to the observed signals. Title: Geological and geochemical contraints on the isotopic composition of interstitial waters from the Hydrate Ridge region, Cascadia Continental margin Author: Torres, Marta E., Matsumoto, R., Tomaru, A. M., Borowski, Walter S. The isotopic compositions of interstitial waters collected from Hydrate Ridge during Ocean Drilling Program Leg 204 were measured to evaluate the fluid evolution of this accretionary prism. At shallow depths, the dissolved Cl- concentrations and δD and δ¹⁸O values of the interstitial water reflect changes in the salinity and the isotopic compositions of seawater from the Last Glacial Maximum to the present. The presence of disseminated gas hydrates, which is well identified by discrete low Cl- anomalies within the gas hydrate stability zone, is accompanied by high δD and δ¹⁸O values of the freshened fluids. This is consistent with incorporation of heavy isotopes into the gas hydrate lattice, which is also apparent in the signals observed at the ridge summit. Here, massive gas hydrate formation in the upper 20 meters below seafloor leads the formation of brines with dissolved Cl- concentrations as high as 1400 mM. The interstitial waters sampled near massive gas hydrates at the ridge summit are extremely depleted in D and ¹⁸O. Clay mineral dehydration within the deep prism results in a progressive decrease in Cl¯ and δD with depth. Dehydration temperature estimates based on those data likely suggest a progressive increase in the temperature of isotopic fractionation between clay and water with distance from the prism toe. The oxygen isotope data probably reflect the combined effects of clay dehydration, carbonate precipitation, and alteration of oceanic basement; however, there are not enough data to constrain the relative contribution of these processes to the observed signals. Close

• 62. [Article] Leg 204 synthesis : gas hydrate distribution and dynamics in the Central Cascadia accretionary complex

  Ocean Drilling Program (ODP) Leg 204 to Hydrate Ridge, located on the continental slope offshore Oregon (USA), was the first drilling expedition dedicated to understanding gas hydrate processes in accretionary complexes ...

  Citation × Citation Citation Abstract Copy Title: Leg 204 synthesis : gas hydrate distribution and dynamics in the Central Cascadia accretionary complex Author: Torres, Marta E., Bohrmann, G., Colwell, Frederick, Tréhu, Anne Martine Ocean Drilling Program (ODP) Leg 204 to Hydrate Ridge, located on the continental slope offshore Oregon (USA), was the first drilling expedition dedicated to understanding gas hydrate processes in accretionary complexes and provided a testbed for a number of different techniques for estimating the gas hydrate content of sediments. It was also the first time that (1) digital infrared scans of core temperature were systematically recorded for all cores from within or near the gas hydrate stability zone, facilitating identification of gas hydrate samples for further study, (2) hydrate-bearing cores were recovered and logged at in situ pressure, and (3) ODP allowed acquisition of logging-while-drilling data prior to coring at a given site, providing an initial comprehensive estimate of gas hydrate distribution that was used to design the subsequent coring program. Gas hydrate estimates based on a variety of geophysical and geochemical techniques indicate a heterogeneous distribution of gas hydrate, which results in part because of two distinct regimes for delivery of gas to the gas hydrate stability zone. In the “reaction regime,” which is pervasive throughout the study region, the average gas hydrate content of the sediments is relatively low (2%–8% of the pore space), no gas hydrate is present in the upper ~30 meters below seafloor (mbsf) because the methane content of the pore water is below saturation, and the fine-scale distribution of gas hydrate depends strongly on lithology. Superimposed on the reaction regime is a “transport-dominated regime” in which gas is focused into a stratigraphically controlled conduit and is transported as free gas to the structural summit. At the summit, high gas pressure drives free gas into and through the gas hydrate stability zone, resulting in a shallow deposit in which gas hydrate comprises ~25% of the total sediment volume to a depth of ~25 mbsf. Geochemical data indicate that most of the gas that forms the summit deposit has migrated from greater depth and has either a thermogenic or altered biogenic character, and modeling suggests that abundant free gas is needed to form gas hydrate in these conditions. Although this deposit contains only ~2% of the estimated total volume of methane trapped in gas hydrate within the study region, it may be particularly susceptible to destabilization in response to oceanographic change. Title: Leg 204 synthesis : gas hydrate distribution and dynamics in the Central Cascadia accretionary complex Author: Torres, Marta E., Bohrmann, G., Colwell, Frederick, Tréhu, Anne Martine Ocean Drilling Program (ODP) Leg 204 to Hydrate Ridge, located on the continental slope offshore Oregon (USA), was the first drilling expedition dedicated to understanding gas hydrate processes in accretionary complexes and provided a testbed for a number of different techniques for estimating the gas hydrate content of sediments. It was also the first time that (1) digital infrared scans of core temperature were systematically recorded for all cores from within or near the gas hydrate stability zone, facilitating identification of gas hydrate samples for further study, (2) hydrate-bearing cores were recovered and logged at in situ pressure, and (3) ODP allowed acquisition of logging-while-drilling data prior to coring at a given site, providing an initial comprehensive estimate of gas hydrate distribution that was used to design the subsequent coring program. Gas hydrate estimates based on a variety of geophysical and geochemical techniques indicate a heterogeneous distribution of gas hydrate, which results in part because of two distinct regimes for delivery of gas to the gas hydrate stability zone. In the “reaction regime,” which is pervasive throughout the study region, the average gas hydrate content of the sediments is relatively low (2%–8% of the pore space), no gas hydrate is present in the upper ~30 meters below seafloor (mbsf) because the methane content of the pore water is below saturation, and the fine-scale distribution of gas hydrate depends strongly on lithology. Superimposed on the reaction regime is a “transport-dominated regime” in which gas is focused into a stratigraphically controlled conduit and is transported as free gas to the structural summit. At the summit, high gas pressure drives free gas into and through the gas hydrate stability zone, resulting in a shallow deposit in which gas hydrate comprises ~25% of the total sediment volume to a depth of ~25 mbsf. Geochemical data indicate that most of the gas that forms the summit deposit has migrated from greater depth and has either a thermogenic or altered biogenic character, and modeling suggests that abundant free gas is needed to form gas hydrate in these conditions. Although this deposit contains only ~2% of the estimated total volume of methane trapped in gas hydrate within the study region, it may be particularly susceptible to destabilization in response to oceanographic change. Close

• 63. [Article] Tectonic model of the Pacific-North American plate boundary in the Gulf of Alaska from broadband analysis of the 1979 St. Elias, Alaska, earthquake and its aftershocks

  The St. Elias, Alaska earthquake of 28 February, 1979 (M s 7.2) is reanalyzed using broadband teleseismic body waves and long-period surface waves because of unresolved questions about its depth, focal ...

  Citation × Citation Citation Abstract Copy Title: Tectonic model of the Pacific-North American plate boundary in the Gulf of Alaska from broadband analysis of the 1979 St. Elias, Alaska, earthquake and its aftershocks Author: Lerner-Lam, Arthur L., Nabelek, John L., Estabrook, Charles H. The St. Elias, Alaska earthquake of 28 February, 1979 (M s 7.2) is reanalyzed using broadband teleseismic body waves and long-period surface waves because of unresolved questions about its depth, focal mechanism, seismic moment, and location in a seismic gap. Teleseismic waveforms are simultaneously inverted to determine the source mechanism, seismic moment, rupture history and centroid depth. These data are well modeled with a point source propagating in the ESE direction with an average kinematic rupture velocity of 2.5 km/s. The best-fitting source mechanism indicates underthrusting on a NE-dipping plane. The mainshock depth of 24 km and the depth of aftershocks determined from inversions are consistent with locations on the gently dipping main thrust of the Pacific-North American plate boundary. These depths are substantially different from those of earlier body wave studies and regional seismic network aftershock depth determinations but are in accord with the Harvard Centroid-Moment Tensor and International Seismological Centre determinations. The seismic moment determined from body waves is 9.4x10^19N-m( 7 .3). The spatial and temporal distribution of moment release indicates that the St. Elias earthquake was a complex rupture consisting of two distinct subevents within 38 s of the initial onset, followed by low moment release during the next 34 s. Earlier studies indicated an unusual amount of surface wave energy at very long periods (> 200 s) that led some workers to suggest that St. Elias was a "slow" earthquake. Our broadband modeling does not require more than 34 s of additional moment release after the first two subevents. Moreover, we are able to match the phase and amplitude of 200-s Love and Rayleigh waves with a Thrust fault point source of moment 1.3x10^20N-m (Mw 7.4) located at the body wave centroid. The moment difference is not discernible with body waves for moment evenly distributed over 72 s. Thus, the St. Elias earthquake is not slow with respect to 200-s surface waves but is complex with regard to the broadband body waves. Upper plate structure apparently controlled the gross characteristics of rupture. The rupture direction parallels mapped upper plate faults. Rupture propagated unilaterally to the ESE, with little initial moment release, as a shallow, north-dipping thrust that later changed to more steeply NE dipping with a large right-lateral strike-slip component. The locations and source mechanisms of these subevents and locations of aftershocks define a shallow dipping surface at the eastern edge of the Pacific plate. Moreover, the component of strike-slip motion increases with time in the mainshock implying that the transition to strike-slip faulting occurs along the plate interface. The estimated nucleation point of the second subevent coincides with a large concentration of aftershocks interpreted as representing a barrier to continuous rupture associated with the northern-most boundary of the Yakutat terrane. Joint relocation of aftershocks suggests that the main plate boundary may be offset vertically by 5-10 km as a result of this structure. The southern part of the aftershock zone, while containing many aftershocks, appears not to have ruptured coseismically, but may have failed later by aseismic creep as seen in geodetic measurements. Faults associated with the Malaspina fault system (the onshore extension of the Aleutian trench) appear to be the surface expression of the underthrusting plate boundary; however, upper plate deformation is widespread because of the collision of the Yakutat terrane. The convergence direction may explain the lack of a highly active Wadati- Benioff zone downdip of the St. Elias zone. The neotectonic deformation of the Chugach-St. Elias mountains is probably related to collision and subduction of the Yakutat terrane: A terrane in the process of accreting and subducting will cause considerable upper plate deformation over a wide zone. Once subduction of a terrane has begun, deformation may then become localized. Title: Tectonic model of the Pacific-North American plate boundary in the Gulf of Alaska from broadband analysis of the 1979 St. Elias, Alaska, earthquake and its aftershocks Author: Lerner-Lam, Arthur L., Nabelek, John L., Estabrook, Charles H. The St. Elias, Alaska earthquake of 28 February, 1979 (M s 7.2) is reanalyzed using broadband teleseismic body waves and long-period surface waves because of unresolved questions about its depth, focal mechanism, seismic moment, and location in a seismic gap. Teleseismic waveforms are simultaneously inverted to determine the source mechanism, seismic moment, rupture history and centroid depth. These data are well modeled with a point source propagating in the ESE direction with an average kinematic rupture velocity of 2.5 km/s. The best-fitting source mechanism indicates underthrusting on a NE-dipping plane. The mainshock depth of 24 km and the depth of aftershocks determined from inversions are consistent with locations on the gently dipping main thrust of the Pacific-North American plate boundary. These depths are substantially different from those of earlier body wave studies and regional seismic network aftershock depth determinations but are in accord with the Harvard Centroid-Moment Tensor and International Seismological Centre determinations. The seismic moment determined from body waves is 9.4x10^19N-m( 7 .3). The spatial and temporal distribution of moment release indicates that the St. Elias earthquake was a complex rupture consisting of two distinct subevents within 38 s of the initial onset, followed by low moment release during the next 34 s. Earlier studies indicated an unusual amount of surface wave energy at very long periods (> 200 s) that led some workers to suggest that St. Elias was a "slow" earthquake. Our broadband modeling does not require more than 34 s of additional moment release after the first two subevents. Moreover, we are able to match the phase and amplitude of 200-s Love and Rayleigh waves with a Thrust fault point source of moment 1.3x10^20N-m (Mw 7.4) located at the body wave centroid. The moment difference is not discernible with body waves for moment evenly distributed over 72 s. Thus, the St. Elias earthquake is not slow with respect to 200-s surface waves but is complex with regard to the broadband body waves. Upper plate structure apparently controlled the gross characteristics of rupture. The rupture direction parallels mapped upper plate faults. Rupture propagated unilaterally to the ESE, with little initial moment release, as a shallow, north-dipping thrust that later changed to more steeply NE dipping with a large right-lateral strike-slip component. The locations and source mechanisms of these subevents and locations of aftershocks define a shallow dipping surface at the eastern edge of the Pacific plate. Moreover, the component of strike-slip motion increases with time in the mainshock implying that the transition to strike-slip faulting occurs along the plate interface. The estimated nucleation point of the second subevent coincides with a large concentration of aftershocks interpreted as representing a barrier to continuous rupture associated with the northern-most boundary of the Yakutat terrane. Joint relocation of aftershocks suggests that the main plate boundary may be offset vertically by 5-10 km as a result of this structure. The southern part of the aftershock zone, while containing many aftershocks, appears not to have ruptured coseismically, but may have failed later by aseismic creep as seen in geodetic measurements. Faults associated with the Malaspina fault system (the onshore extension of the Aleutian trench) appear to be the surface expression of the underthrusting plate boundary; however, upper plate deformation is widespread because of the collision of the Yakutat terrane. The convergence direction may explain the lack of a highly active Wadati- Benioff zone downdip of the St. Elias zone. The neotectonic deformation of the Chugach-St. Elias mountains is probably related to collision and subduction of the Yakutat terrane: A terrane in the process of accreting and subducting will cause considerable upper plate deformation over a wide zone. Once subduction of a terrane has begun, deformation may then become localized. Close

• 64. [Article] The sources of volatile and fluid-mobile elements in the Sunda arc: A melt inclusion study from Kawah Ijen and Tambora volcanoes, Indonesia

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/.

  Citation × Citation Citation Abstract Copy Title: The sources of volatile and fluid-mobile elements in the Sunda arc: A melt inclusion study from Kawah Ijen and Tambora volcanoes, Indonesia Author: Williams-Jones, Anthony E., Vigouroux, Nathalie, Kent, Adam J. R., Wallace, Paul J., Kelley, Katherine, Williams-Jones, Glyn This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/. Title: The sources of volatile and fluid-mobile elements in the Sunda arc: A melt inclusion study from Kawah Ijen and Tambora volcanoes, Indonesia Author: Williams-Jones, Anthony E., Vigouroux, Nathalie, Kent, Adam J. R., Wallace, Paul J., Kelley, Katherine, Williams-Jones, Glyn This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/gc/. Close

• 65. [Article] Effects of mesoscale processes on phytoplankton chlorophyll off Baja California

  This is the publisher’s final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://sites.agu.org/.

  Citation × Citation Citation Abstract Copy Title: Effects of mesoscale processes on phytoplankton chlorophyll off Baja California Author: Gaxiola-Castro, Gilberto, Strub, P. Ted, T. Leticia Espinosa-Carreon, T. Leticia, Beier, Emilio, Kurczyn, J. A. This is the publisher’s final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://sites.agu.org/. Title: Effects of mesoscale processes on phytoplankton chlorophyll off Baja California Author: Gaxiola-Castro, Gilberto, Strub, P. Ted, T. Leticia Espinosa-Carreon, T. Leticia, Beier, Emilio, Kurczyn, J. A. This is the publisher’s final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://sites.agu.org/. Close

• 66. [Article] The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier ...

  Citation × Citation Citation Abstract Copy Title: The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin Author: Haley, Brian A., Pohlman, John W., Kim, Ji-Hoon, Lee, Young-Joo, Riedel, Michael, Kastner, Miriam, Torres, Marta E. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/. Title: The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin Author: Haley, Brian A., Pohlman, John W., Kim, Ji-Hoon, Lee, Young-Joo, Riedel, Michael, Kastner, Miriam, Torres, Marta E. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/. Close

• 67. [Article] Imaging crustal structure in southwestern Washington with smalll magnetometer arrays

  We use data from a series of small (three to five stations) overlapping magnetovariational (MV) arrays to image variations of vertically integrated electrical conductivity in the crust of southwestern ...

  Citation × Citation Citation Abstract Copy Title: Imaging crustal structure in southwestern Washington with smalll magnetometer arrays Author: Booker, John R., Egbert, Gary D. We use data from a series of small (three to five stations) overlapping magnetovariational (MV) arrays to image variations of vertically integrated electrical conductivity in the crust of southwestern Washington. Two principal structures are revealed: a large north-south trending anomaly (the southern Washington Cascades Conductor (SWCC), which has been detected by several previous induction experiments), and a smaller anomaly which branches off the SWCC just north of Mount St. Helens and trends westward beneath the Chehallis Basin. A weaker east-west trending anomaly is evident farther to the north beneath southern Puget Sound. The MV results concerning the SWCC are reasonably consistent with the model of Stanley et al. (1987), who interpret he anomaly as a suture zone of mid-late Eocene age, but the array data allows us to map the horizontal extent and complex three-dimensional character of the SWCC in greater detail. We suggest that the SWCC represents a section of the early Cenozoic subduction zone which is analogous to the present-day Olympic Peninsula. In the region west of the Cascades, the array data show that crustal conductivity is distinctly three dimensional, consisting of highly resistive blocks (crystalline rocks) separated (in the upper 5-10 km at least) by interconnected narrow regions of higher conductivity (sedimentary units). This pattern of conductivity variations is consistent with the inferred origin of the region as a seamount complex, which was subsequently broken into discrete blocks which have been thrust together during and after accretion to the North American continent. The distribution of anomalous electric currents and our model for crustal conductance are in striking agreement with a variety of other geophysical constraints, including gravity, magnetics, present crustal seismicity, and the pattern of recent volcanic vents. The St. Helens seismic zone (SHZ), which coincides with the western edge of the broad southern portion of the SWCC, is abruptly terminatedi n the north by the smaller east-west trending conductive zone. North of the SHZ near Mount Rainier, seismicity is concentrated in a narrow band coincident with the very narrow northern portion of the SWCC. In addition, volcanic vents are concentrated around the edges of the SWCC but are rare in the interior of the zone of high conductivity. The magnetometer array data thus suggest that present patterns of crustal deformation and volcanism are in part controlled by the complex tectonic history (and resulting crustal structure) of the region. Title: Imaging crustal structure in southwestern Washington with smalll magnetometer arrays Author: Booker, John R., Egbert, Gary D. We use data from a series of small (three to five stations) overlapping magnetovariational (MV) arrays to image variations of vertically integrated electrical conductivity in the crust of southwestern Washington. Two principal structures are revealed: a large north-south trending anomaly (the southern Washington Cascades Conductor (SWCC), which has been detected by several previous induction experiments), and a smaller anomaly which branches off the SWCC just north of Mount St. Helens and trends westward beneath the Chehallis Basin. A weaker east-west trending anomaly is evident farther to the north beneath southern Puget Sound. The MV results concerning the SWCC are reasonably consistent with the model of Stanley et al. (1987), who interpret he anomaly as a suture zone of mid-late Eocene age, but the array data allows us to map the horizontal extent and complex three-dimensional character of the SWCC in greater detail. We suggest that the SWCC represents a section of the early Cenozoic subduction zone which is analogous to the present-day Olympic Peninsula. In the region west of the Cascades, the array data show that crustal conductivity is distinctly three dimensional, consisting of highly resistive blocks (crystalline rocks) separated (in the upper 5-10 km at least) by interconnected narrow regions of higher conductivity (sedimentary units). This pattern of conductivity variations is consistent with the inferred origin of the region as a seamount complex, which was subsequently broken into discrete blocks which have been thrust together during and after accretion to the North American continent. The distribution of anomalous electric currents and our model for crustal conductance are in striking agreement with a variety of other geophysical constraints, including gravity, magnetics, present crustal seismicity, and the pattern of recent volcanic vents. The St. Helens seismic zone (SHZ), which coincides with the western edge of the broad southern portion of the SWCC, is abruptly terminatedi n the north by the smaller east-west trending conductive zone. North of the SHZ near Mount Rainier, seismicity is concentrated in a narrow band coincident with the very narrow northern portion of the SWCC. In addition, volcanic vents are concentrated around the edges of the SWCC but are rare in the interior of the zone of high conductivity. The magnetometer array data thus suggest that present patterns of crustal deformation and volcanism are in part controlled by the complex tectonic history (and resulting crustal structure) of the region. Close

• 68. [Article] Segmentation of the Blanco Transform Fault Zone from earthquake analysis: Complex tectonics of an oceanic transform fault

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Segmentation of the Blanco Transform Fault Zone from earthquake analysis: Complex tectonics of an oceanic transform fault Author: Braunmiller, Jochen, Nábělek, John Copyrighted by American Geophysical Union. Title: Segmentation of the Blanco Transform Fault Zone from earthquake analysis: Complex tectonics of an oceanic transform fault Author: Braunmiller, Jochen, Nábělek, John Copyrighted by American Geophysical Union. Close

• 69. [Article] Rotation and plate locking at the southern Cascadia subduction zone

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Rotation and plate locking at the southern Cascadia subduction zone Author: Goldfinger, Chris, Nabelek, John L., Smith, Curt, Long, Maureen D., Johnson, Cheryl K., Zwick, Peter C., McCaffrey, Robert Copyrighted by American Geophysical Union. Title: Rotation and plate locking at the southern Cascadia subduction zone Author: Goldfinger, Chris, Nabelek, John L., Smith, Curt, Long, Maureen D., Johnson, Cheryl K., Zwick, Peter C., McCaffrey, Robert Copyrighted by American Geophysical Union. Close

• 70. [Article] Distribution and height of methane bubble plumes on the Cascadia Margin characterized by acoustic imaging

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Distribution and height of methane bubble plumes on the Cascadia Margin characterized by acoustic imaging Author: Collier, Robert W., Rehder, Gregor, Suess, Erwin, Tréhu, Anne Martine, Heeschen, Katja U. Copyrighted by American Geophysical Union. Title: Distribution and height of methane bubble plumes on the Cascadia Margin characterized by acoustic imaging Author: Collier, Robert W., Rehder, Gregor, Suess, Erwin, Tréhu, Anne Martine, Heeschen, Katja U. Copyrighted by American Geophysical Union. Close

• 71. [Article] Interactions between deformation and fluids in the frontal thrust region of the NanTroSEIZE transect offshore the Kii Peninsula, Japan: Results from IODP Expedition 316 Sites C0006 and C0007

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Interactions between deformation and fluids in the frontal thrust region of the NanTroSEIZE transect offshore the Kii Peninsula, Japan: Results from IODP Expedition 316 Sites C0006 and C0007 Author: Tsutsumi, A., Kitamura, Y., Fergusson, C., Chester, F., Su, X., Riedinger, N., Ujiee, K., Sakaguchi, A., Nicholson, U., Zhao, X., Moore, G., Knuth, M., Harris, Robert N., Louis, L., Kimura, G., Yamaguchi, A., Sceaton, E., Girault, F., Curewitz, D., Milliken, K., Li, C.-F., Solomon, E., Fabbri, O., Goldsby, D., Jiang, T., Claesson Liljedahl, L., Stasser, M., Inagaki, F. Copyrighted by American Geophysical Union. Title: Interactions between deformation and fluids in the frontal thrust region of the NanTroSEIZE transect offshore the Kii Peninsula, Japan: Results from IODP Expedition 316 Sites C0006 and C0007 Author: Tsutsumi, A., Kitamura, Y., Fergusson, C., Chester, F., Su, X., Riedinger, N., Ujiee, K., Sakaguchi, A., Nicholson, U., Zhao, X., Moore, G., Knuth, M., Harris, Robert N., Louis, L., Kimura, G., Yamaguchi, A., Sceaton, E., Girault, F., Curewitz, D., Milliken, K., Li, C.-F., Solomon, E., Fabbri, O., Goldsby, D., Jiang, T., Claesson Liljedahl, L., Stasser, M., Inagaki, F. Copyrighted by American Geophysical Union. Close

• 72. [Article] Oblique strike-slip faulting of the central Cascadia submarine forearc

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Oblique strike-slip faulting of the central Cascadia submarine forearc Author: Yeats, Robert S., Goldfinger, Chris, Hummon, Cheryl, McNeill, Lisa, Kulm, LaVerne D. Copyrighted by American Geophysical Union. Title: Oblique strike-slip faulting of the central Cascadia submarine forearc Author: Yeats, Robert S., Goldfinger, Chris, Hummon, Cheryl, McNeill, Lisa, Kulm, LaVerne D. Copyrighted by American Geophysical Union. Close

• 73. [Article] Methane sources, distributions, and fluxes from vent sites at Hydrate Ridge, Cascadia Margin

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Methane sources, distributions, and fluxes from vent sites at Hydrate Ridge, Cascadia Margin Author: Collier, Robert W., Rehder, Gregor, Suess, Erwin, Linke, Peter, de Angelis, Marie A., Heeschen, Katja U., Klinkhammer, Gary P. Copyrighted by American Geophysical Union. Title: Methane sources, distributions, and fluxes from vent sites at Hydrate Ridge, Cascadia Margin Author: Collier, Robert W., Rehder, Gregor, Suess, Erwin, Linke, Peter, de Angelis, Marie A., Heeschen, Katja U., Klinkhammer, Gary P. Copyrighted by American Geophysical Union. Close

• 74. [Article] Large fluctuations of dissolved oxygen in the Indian and Pacific oceans during Dansgaard-Oeschger oscillations caused by variations of North Atlantic Deep Water subduction

  Paleoclimate records from glacial Indian and Pacific oceans sediments document millennial-scale fluctuations of subsurface dissolved oxygen levels and denitrification coherent with North Atlantic temperature ...

  Citation × Citation Citation Abstract Copy Title: Large fluctuations of dissolved oxygen in the Indian and Pacific oceans during Dansgaard-Oeschger oscillations caused by variations of North Atlantic Deep Water subduction Author: Hostetler, Steven W., Pedersen, Thomas F., Schmittner, Andreas, Galbraith, Eric D., Zhang, Rong Paleoclimate records from glacial Indian and Pacific oceans sediments document millennial-scale fluctuations of subsurface dissolved oxygen levels and denitrification coherent with North Atlantic temperature oscillations. Yet the mechanism of this teleconnection between the remote ocean basins remains elusive. Here we present model simulations of the oxygen and nitrogen cycles that explain how changes in deepwater subduction in the North Atlantic can cause large and synchronous variations of oxygen minimum zones throughout the Northern Hemisphere of the Indian and Pacific oceans, consistent with the paleoclimate records. Cold periods in the North Atlantic are associated with reduced nutrient delivery to the upper Indo-Pacific oceans, thereby decreasing productivity. Reduced export production diminishes subsurface respiration of organic matter leading to higher oxygen concentrations and less denitrification. This effect of reduced oxygen consumption dominates at low latitudes. At high latitudes in the Southern Ocean and North Pacific, increased mixed layer depths and steepening of isopycnals improve ocean ventilation and oxygen supply to the subsurface. Atmospheric teleconnections through changes in wind-driven ocean circulation modify this basin-scale pattern regionally. These results suggest that changes in the Atlantic Ocean circulation, similar to those projected by climate models to possibly occur in the centuries to come because of anthropogenic climate warming, can have large effects on marine ecosystems and biogeochemical cycles even in remote areas. Title: Large fluctuations of dissolved oxygen in the Indian and Pacific oceans during Dansgaard-Oeschger oscillations caused by variations of North Atlantic Deep Water subduction Author: Hostetler, Steven W., Pedersen, Thomas F., Schmittner, Andreas, Galbraith, Eric D., Zhang, Rong Paleoclimate records from glacial Indian and Pacific oceans sediments document millennial-scale fluctuations of subsurface dissolved oxygen levels and denitrification coherent with North Atlantic temperature oscillations. Yet the mechanism of this teleconnection between the remote ocean basins remains elusive. Here we present model simulations of the oxygen and nitrogen cycles that explain how changes in deepwater subduction in the North Atlantic can cause large and synchronous variations of oxygen minimum zones throughout the Northern Hemisphere of the Indian and Pacific oceans, consistent with the paleoclimate records. Cold periods in the North Atlantic are associated with reduced nutrient delivery to the upper Indo-Pacific oceans, thereby decreasing productivity. Reduced export production diminishes subsurface respiration of organic matter leading to higher oxygen concentrations and less denitrification. This effect of reduced oxygen consumption dominates at low latitudes. At high latitudes in the Southern Ocean and North Pacific, increased mixed layer depths and steepening of isopycnals improve ocean ventilation and oxygen supply to the subsurface. Atmospheric teleconnections through changes in wind-driven ocean circulation modify this basin-scale pattern regionally. These results suggest that changes in the Atlantic Ocean circulation, similar to those projected by climate models to possibly occur in the centuries to come because of anthropogenic climate warming, can have large effects on marine ecosystems and biogeochemical cycles even in remote areas. Close

• 75. [Article] Statistical properties of near surface currents in the California coastal transition zone

  During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the ...

  Citation × Citation Citation Abstract Copy Title: Statistical properties of near surface currents in the California coastal transition zone Author: Beardsley, R. C., Abbott, Mark R., Stanton, T., Stuart, D., Ramp, S., Brink, K. H., Niiler, Pearn P., Huyer, Adriana, 1945- During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the Coastal Transition Zone (CTZ) program. The drifters had large drogues centered at 15 m, and the resulting drifter trajectory data set has been analyzed in terms of its Eulerian and Lagrangian statistics. The CTZ drifter results show that the California Current can be characterized in summer and fall as a meandering coherent jet which on average flows southward to at least 30ºN, the southern end of the study domain. From 39ºN south to about 33ºN, the typical core velocities are of O(300 km) and the current meanders have alongshore wavelengths of O(100–200 km) and onshore-offshore amplitude of O(100–200 km). The lateral movement of this jet leads to large eddy kinetic energies and large eddy diffusivities, especially north of 36ºN. The initial onshore-offshore component of diffusivity is always greater than the alongshore component in the study domain, but at the southern end, the eddy diffusivity is more isotropic, with scalar single particle diffusivity (Kxx + Kyy) of O(8 x 107 cm2 s-1). The eddy diffusivity increases with increasing eddy energy. Finally, a simple volume budget for the 1988 filament observed near 37ºN off Point Arena suggests that subduction can occur in a filament at an average rate of O(10 m d-1) some 200 km offshore, thus allowing the cold water initially in the filament core to sink below the warmer ambient water by the time the surface velocity core has turned back onshore. This process explains why satellite temperature and color imagery tend to “see” only flow proceeding offshore. Title: Statistical properties of near surface currents in the California coastal transition zone Author: Beardsley, R. C., Abbott, Mark R., Stanton, T., Stuart, D., Ramp, S., Brink, K. H., Niiler, Pearn P., Huyer, Adriana, 1945- During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the Coastal Transition Zone (CTZ) program. The drifters had large drogues centered at 15 m, and the resulting drifter trajectory data set has been analyzed in terms of its Eulerian and Lagrangian statistics. The CTZ drifter results show that the California Current can be characterized in summer and fall as a meandering coherent jet which on average flows southward to at least 30ºN, the southern end of the study domain. From 39ºN south to about 33ºN, the typical core velocities are of O(300 km) and the current meanders have alongshore wavelengths of O(100–200 km) and onshore-offshore amplitude of O(100–200 km). The lateral movement of this jet leads to large eddy kinetic energies and large eddy diffusivities, especially north of 36ºN. The initial onshore-offshore component of diffusivity is always greater than the alongshore component in the study domain, but at the southern end, the eddy diffusivity is more isotropic, with scalar single particle diffusivity (Kxx + Kyy) of O(8 x 107 cm2 s-1). The eddy diffusivity increases with increasing eddy energy. Finally, a simple volume budget for the 1988 filament observed near 37ºN off Point Arena suggests that subduction can occur in a filament at an average rate of O(10 m d-1) some 200 km offshore, thus allowing the cold water initially in the filament core to sink below the warmer ambient water by the time the surface velocity core has turned back onshore. This process explains why satellite temperature and color imagery tend to “see” only flow proceeding offshore. Close

• 76. [Article] Probing the Earth’s Deep Interior Through Geochemistry

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by European ...

  Citation × Citation Citation Abstract Copy Title: Probing the Earth’s Deep Interior Through Geochemistry Author: White, William M. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by European Association of Geochemistry and can be found at: http://www.geochemicalperspectives.org/ Title: Probing the Earth’s Deep Interior Through Geochemistry Author: White, William M. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by European Association of Geochemistry and can be found at: http://www.geochemicalperspectives.org/ Close

• 77. [Article] Method to Determine Locations of Tsunami Vertical Evacuation Shelters

  This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://www.springer.com/earth+sciences+and+geogr...

  Citation × Citation Citation Abstract Copy Title: Method to Determine Locations of Tsunami Vertical Evacuation Shelters Author: Park, Sangki, Gupta, Rakesh, van de Lindt, John W., Cox, Daniel This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://www.springer.com/earth+sciences+and+geography/natural+hazards/journal/11069. Title: Method to Determine Locations of Tsunami Vertical Evacuation Shelters Author: Park, Sangki, Gupta, Rakesh, van de Lindt, John W., Cox, Daniel This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://www.springer.com/earth+sciences+and+geography/natural+hazards/journal/11069. Close

• 78. [Article] Geostatistical Examination of the Geotechnical Portland BES Databases with Emphasis on Silt

  Willamette Valley silt deposits from historical catastrophic flood events present a difficult problem for subsurface engineers practicing in the Portland, Oregon area. Silts exhibit behavior of two very ...

  Citation × Citation Citation Abstract Copy Title: Geostatistical Examination of the Geotechnical Portland BES Databases with Emphasis on Silt Author: Baumann, Alex K. Year: 2015 Willamette Valley silt deposits from historical catastrophic flood events present a difficult problem for subsurface engineers practicing in the Portland, Oregon area. Silts exhibit behavior of two very well-documented soil types, but publications containing mechanical properties for silts are scant, especially for local silts. Thus, the need for links between real Portland site investigation data and silt properties is high. To further exemplify the need for documented knowledge of local silts, this project reveals the evolving state of practice to incorporate more Pacific Northwest seismic analyses in preparation for a subduction zone earthquake. The geotechnical Portland BES databases contain thousands of private sector (PrS) and public sector (PbS) geotechnical documents from sites in the Portland area. The PrS database includes approximately 7,000 geotechnical documents for PrS projects dating primarily from the mid 1900’s to 2009 for a range of project types. A statistically significant random sample of 1,500 documents from the PrS database was organized and analyzed. The approximate 1,000 documents in the PbS database containing boring logs can be linked to location through a pre-existing GIS layer. The statistically significant sample from the PrS database and the GIS layer from the PbS database were compared spatially to reveal clusters of documented geotechnical projects. An isolated cluster of 80 full geotechnical reports in the Downtown, Portland area from reputable practitioners was examined for standard penetration blow counts, equipment information, groundwater table depths, soil descriptions, unit weights, drill dates, and moisture contents to capture a range of correlated peak effective friction angles for different compositions of silt. The project types and report contents from the PrS database were analyzed in the Downtown area, and conclusions were made on the percentages of project types and apparent chronological trends in report content. Title: Geostatistical Examination of the Geotechnical Portland BES Databases with Emphasis on Silt Author: Baumann, Alex K. Year: 2015 Willamette Valley silt deposits from historical catastrophic flood events present a difficult problem for subsurface engineers practicing in the Portland, Oregon area. Silts exhibit behavior of two very well-documented soil types, but publications containing mechanical properties for silts are scant, especially for local silts. Thus, the need for links between real Portland site investigation data and silt properties is high. To further exemplify the need for documented knowledge of local silts, this project reveals the evolving state of practice to incorporate more Pacific Northwest seismic analyses in preparation for a subduction zone earthquake. The geotechnical Portland BES databases contain thousands of private sector (PrS) and public sector (PbS) geotechnical documents from sites in the Portland area. The PrS database includes approximately 7,000 geotechnical documents for PrS projects dating primarily from the mid 1900’s to 2009 for a range of project types. A statistically significant random sample of 1,500 documents from the PrS database was organized and analyzed. The approximate 1,000 documents in the PbS database containing boring logs can be linked to location through a pre-existing GIS layer. The statistically significant sample from the PrS database and the GIS layer from the PbS database were compared spatially to reveal clusters of documented geotechnical projects. An isolated cluster of 80 full geotechnical reports in the Downtown, Portland area from reputable practitioners was examined for standard penetration blow counts, equipment information, groundwater table depths, soil descriptions, unit weights, drill dates, and moisture contents to capture a range of correlated peak effective friction angles for different compositions of silt. The project types and report contents from the PrS database were analyzed in the Downtown area, and conclusions were made on the percentages of project types and apparent chronological trends in report content. Close

• 79. [Article] Webinar: Developing Practical Dynamic Evaluation Methods for Transportation Structures

  Deteriorating transportation infrastructure is constantly in the news. Government agencies at all levels are pursuing methods to monitor structural health, so that they can prioritize repairs. In Oregon, ...

  Citation × Citation Citation Abstract Copy Title: Webinar: Developing Practical Dynamic Evaluation Methods for Transportation Structures Author: Riley, Charles Year: 2017 Deteriorating transportation infrastructure is constantly in the news. Government agencies at all levels are pursuing methods to monitor structural health, so that they can prioritize repairs. In Oregon, the Cascadia Subduction Zone megathrust earthquake looms as a significant natural hazard for which our transportation network is ill-prepared. The Oregon Department of Transportation (ODOT) estimates that it will take around $2.6 billion over seven years to repair or replace many of the existing bridges in the state’s network to maintain lifeline routes after a Cascadia event. Funding for the scenarios envisioned by ODOT is not forthcoming, and the project described in this webinar is aimed at creating a tool to support visual inspection of bridges for determining the extent of damage. The work presented in this webinar has evolved out of NITC-funded research and into a feasibility study of relatively simple but effective field methods for transportation structure dynamic evaluation. The primary driver for the methods under investigation is the advent of robust mobile apps that can process data from on-board accelerometers in real time. The goal of this work is to identify an easily deployed system to evaluate the dynamic response of a structure (commonly referred to as modal testing). Assuming such a system can be developed and deployed to record baseline data prior to the Cascadia event, the same system could be used after the event, or any significant event for that matter, to assist in determining if a structure has sustained damage that would limit its safe return to service. This webinar will describe the development and use of various tools for conducting modal testing in the field. After viewing the webinar, attendees should be able to: Describe the scale of the everyday and future hazards facing Oregon bridges Explain the relationship of structural parameters to dynamic response Describe a framework for conducting dynamic evaluation of structures to determine dominant modal frequencies Summarize the results of preliminary field studies using ambient traffic and forced vibration in conjunction with mobile-device based data acquisition Use mobile devices and apps to acquire acceleration data Title: Webinar: Developing Practical Dynamic Evaluation Methods for Transportation Structures Author: Riley, Charles Year: 2017 Deteriorating transportation infrastructure is constantly in the news. Government agencies at all levels are pursuing methods to monitor structural health, so that they can prioritize repairs. In Oregon, the Cascadia Subduction Zone megathrust earthquake looms as a significant natural hazard for which our transportation network is ill-prepared. The Oregon Department of Transportation (ODOT) estimates that it will take around $2.6 billion over seven years to repair or replace many of the existing bridges in the state’s network to maintain lifeline routes after a Cascadia event. Funding for the scenarios envisioned by ODOT is not forthcoming, and the project described in this webinar is aimed at creating a tool to support visual inspection of bridges for determining the extent of damage. The work presented in this webinar has evolved out of NITC-funded research and into a feasibility study of relatively simple but effective field methods for transportation structure dynamic evaluation. The primary driver for the methods under investigation is the advent of robust mobile apps that can process data from on-board accelerometers in real time. The goal of this work is to identify an easily deployed system to evaluate the dynamic response of a structure (commonly referred to as modal testing). Assuming such a system can be developed and deployed to record baseline data prior to the Cascadia event, the same system could be used after the event, or any significant event for that matter, to assist in determining if a structure has sustained damage that would limit its safe return to service. This webinar will describe the development and use of various tools for conducting modal testing in the field. After viewing the webinar, attendees should be able to: Describe the scale of the everyday and future hazards facing Oregon bridges Explain the relationship of structural parameters to dynamic response Describe a framework for conducting dynamic evaluation of structures to determine dominant modal frequencies Summarize the results of preliminary field studies using ambient traffic and forced vibration in conjunction with mobile-device based data acquisition Use mobile devices and apps to acquire acceleration data Close

• 80. [Article] The Effects of Debris Loading on the Performance of a Tsunami Evacuation Building for Life Safety

  In recent years, tsunami events have caused great devastation and loss of life around the globe. The coast of Oregon is highly vulnerable to a nearfield tsunami event caused by a Cascadia Subduction Zone ...

  Citation × Citation Citation Abstract Copy Title: The Effects of Debris Loading on the Performance of a Tsunami Evacuation Building for Life Safety Author: Snyder, Snyder In recent years, tsunami events have caused great devastation and loss of life around the globe. The coast of Oregon is highly vulnerable to a nearfield tsunami event caused by a Cascadia Subduction Zone earthquake, yet lacks a clear plan for evacuation and disaster mitigation. Vertical evacuation is a proposed tsunami evacuation strategy that has been implemented in Japan and Hawaii. The City of Cannon Beach, Oregon wishes to build a City Hall building which will also serve as a vertical tsunami evacuation building (TEB). The study presented herein is one portion of a larger study to investigate a number of aspects to be considered in the design of this structure and future TEBs. This study explores the effects of debris loading, specifically debris damming, on open, columnar design coastal structures intended for use as TEBs. A generalized 1:25 scale model of the Cannon Beach City Hall building was utilized to test the relationship between leading face blocked area and force. The percentage and pattern of blocked area are varied independently. The data reveal that there is a positive relationship between blocked area and force experienced by the specimen, however pattern does not appear to effect this relationship. Title: The Effects of Debris Loading on the Performance of a Tsunami Evacuation Building for Life Safety Author: Snyder, Snyder In recent years, tsunami events have caused great devastation and loss of life around the globe. The coast of Oregon is highly vulnerable to a nearfield tsunami event caused by a Cascadia Subduction Zone earthquake, yet lacks a clear plan for evacuation and disaster mitigation. Vertical evacuation is a proposed tsunami evacuation strategy that has been implemented in Japan and Hawaii. The City of Cannon Beach, Oregon wishes to build a City Hall building which will also serve as a vertical tsunami evacuation building (TEB). The study presented herein is one portion of a larger study to investigate a number of aspects to be considered in the design of this structure and future TEBs. This study explores the effects of debris loading, specifically debris damming, on open, columnar design coastal structures intended for use as TEBs. A generalized 1:25 scale model of the Cannon Beach City Hall building was utilized to test the relationship between leading face blocked area and force. The percentage and pattern of blocked area are varied independently. The data reveal that there is a positive relationship between blocked area and force experienced by the specimen, however pattern does not appear to effect this relationship. Close

• 81. [Article] Geology and geochemistry of Juniper Ridge, Horsehead Mountain and Burns Butte : implications for the petrogenesis of silicic magma on the High Lava Plains, southeastern Oregon

  The Juniper Ridge volcanic complex is located in the High Lava Plains Province of southeastern Oregon, a wide zone of bimodal volcanism and faulting that marks the northern limit of widespread Basin and ...

  Citation × Citation Citation Abstract Copy Title: Geology and geochemistry of Juniper Ridge, Horsehead Mountain and Burns Butte : implications for the petrogenesis of silicic magma on the High Lava Plains, southeastern Oregon Author: MacLean, James W. The Juniper Ridge volcanic complex is located in the High Lava Plains Province of southeastern Oregon, a wide zone of bimodal volcanism and faulting that marks the northern limit of widespread Basin and Range-style faulting in the northern Great Basin Province. Rhyolite dome complexes are progressively younger to the northwest along the High Lava Plains, providing a mirror-image to age-progressive silicic volcanism on the Snake River Plain in southern Idaho. 40Ar-39Ar dating of rocks from western and eastern Juniper Ridge (5.70 ± 0.02 Ma and 6.87 ± 0.02 Ma, respectively) and Burns Butte (7.75 ± 0.06 Ma) confirms the overall age progression, and shows that age relations within the Juniper Ridge complex are consistent with the trend. Horsehead Mountain (15.54 ± 0.03 Ma) predates the age progression altogether. Rocks at both eastern Juniper Ridge and western Juniper Ridge are overlain by diktytaxitic olivine basalt flows similar to regional high-alumina olivine tholeiites (HAOTs). At western Juniper Ridge, high-silica rhyolite flows overlie lower-silica rhyolite and hybrid andesite flows. At eastern Juniper Ridge, a suite of intermediate rocks ranging from basaltic andesite to dacite overlies a series of rhyolite flows. Rocks at Burns Butte consist of high-silica rhyolite, porphyritic dacite and rhyodacite, and andesite. Field and petrographic observations, including mixing textures, inclusions, and xenocrysts, along with straight-line relationships on chemical diagrams, show that the intermediate rocks at western Juniper Ridge formed by mixing between high-silica rhyolite magma and slightly evolved HAOT, probably at the base of a large silicic magma chamber. In contrast, curvilinear geochemical trends and an internally consistent four-stage major and trace element model suggest that intermediate rocks at eastern Juniper Ridge evolved in small, unconnected magma chambers by removal of olivine, plagioclase, clinopyroxene, and magnetite from a primitive HAOT parent, accompanied by contamination by up to 22 percent rhyolite. Unusually elevated concentrations of incompatible trace elements in the Squaw Butte basaltic andesite were produced by either zone refining or combined fractionation and recharge. The least-evolved rhyolites at eastern and western Juniper Ridge have lower rare-earth element concentrations than the intermediate fractionates at eastern Juniper Ridge, thus precluding an origin by crystal fractionation from the observed intermediate rocks, but have major element compositions close to those of experimental dehydration melts of amphibolite. The rhyolites probably originated as dehydration melts of an amphibolite lower crust, which were subsequently modified by removal of quartz, sanidine, plagioclase, clinopyroxene and zircon. At western Juniper Ridge, the fractionating assemblage probably included trace allanite. Rhyolites from dome complexes and ash-flow tufts of the 5- to 10-Ma portion of the ageprogressive trend show systematic trace element variations with position along the trend. Dome complexes include Burns Butte, Palomino Butte, eastern and western Juniper Ridge and Glass Buttes; ash-flow tufts include the Devine Canyon Tuft, the Prater Creek Tuft, the Rattlesnake Tuff and the tuft of Buckaroo Lake. From east to west, Y/Nb and Yb/Ta increase, and Ce/Yb decreases in the least-evolved rhyolite in each suite. These variations can be accounted for by a systematic increase in degree of garnet-residual partial melting of amphibolite crust from east to west, correlating either with degree of extension with time along the Brothers fault zone, or with distance from the main axis of faulting. Porphyritic, calc-alkaline andesites and dacites erupted from at least six vents at Horsehead Mountain. Field relationships indicate a general decrease in age from southwest to northeast within the complex. At 15 Ma, calc-alkaline volcanism at Horsehead Mountain predates the age-progressive rhyolftes, and is instead part of an earlier phase of volcanism that produced the Steens and Columbia River flood basalts, along with several other caic-alkaline intermediate centers that are unrelated to subduction. Overlapping rare-earth element patterns of Horsehead Mountain intermediate rocks with those of Steens basalts precludes their derivation by fractionation from the broadly contemporaneous flood basalts. Title: Geology and geochemistry of Juniper Ridge, Horsehead Mountain and Burns Butte : implications for the petrogenesis of silicic magma on the High Lava Plains, southeastern Oregon Author: MacLean, James W. The Juniper Ridge volcanic complex is located in the High Lava Plains Province of southeastern Oregon, a wide zone of bimodal volcanism and faulting that marks the northern limit of widespread Basin and Range-style faulting in the northern Great Basin Province. Rhyolite dome complexes are progressively younger to the northwest along the High Lava Plains, providing a mirror-image to age-progressive silicic volcanism on the Snake River Plain in southern Idaho. 40Ar-39Ar dating of rocks from western and eastern Juniper Ridge (5.70 ± 0.02 Ma and 6.87 ± 0.02 Ma, respectively) and Burns Butte (7.75 ± 0.06 Ma) confirms the overall age progression, and shows that age relations within the Juniper Ridge complex are consistent with the trend. Horsehead Mountain (15.54 ± 0.03 Ma) predates the age progression altogether. Rocks at both eastern Juniper Ridge and western Juniper Ridge are overlain by diktytaxitic olivine basalt flows similar to regional high-alumina olivine tholeiites (HAOTs). At western Juniper Ridge, high-silica rhyolite flows overlie lower-silica rhyolite and hybrid andesite flows. At eastern Juniper Ridge, a suite of intermediate rocks ranging from basaltic andesite to dacite overlies a series of rhyolite flows. Rocks at Burns Butte consist of high-silica rhyolite, porphyritic dacite and rhyodacite, and andesite. Field and petrographic observations, including mixing textures, inclusions, and xenocrysts, along with straight-line relationships on chemical diagrams, show that the intermediate rocks at western Juniper Ridge formed by mixing between high-silica rhyolite magma and slightly evolved HAOT, probably at the base of a large silicic magma chamber. In contrast, curvilinear geochemical trends and an internally consistent four-stage major and trace element model suggest that intermediate rocks at eastern Juniper Ridge evolved in small, unconnected magma chambers by removal of olivine, plagioclase, clinopyroxene, and magnetite from a primitive HAOT parent, accompanied by contamination by up to 22 percent rhyolite. Unusually elevated concentrations of incompatible trace elements in the Squaw Butte basaltic andesite were produced by either zone refining or combined fractionation and recharge. The least-evolved rhyolites at eastern and western Juniper Ridge have lower rare-earth element concentrations than the intermediate fractionates at eastern Juniper Ridge, thus precluding an origin by crystal fractionation from the observed intermediate rocks, but have major element compositions close to those of experimental dehydration melts of amphibolite. The rhyolites probably originated as dehydration melts of an amphibolite lower crust, which were subsequently modified by removal of quartz, sanidine, plagioclase, clinopyroxene and zircon. At western Juniper Ridge, the fractionating assemblage probably included trace allanite. Rhyolites from dome complexes and ash-flow tufts of the 5- to 10-Ma portion of the ageprogressive trend show systematic trace element variations with position along the trend. Dome complexes include Burns Butte, Palomino Butte, eastern and western Juniper Ridge and Glass Buttes; ash-flow tufts include the Devine Canyon Tuft, the Prater Creek Tuft, the Rattlesnake Tuff and the tuft of Buckaroo Lake. From east to west, Y/Nb and Yb/Ta increase, and Ce/Yb decreases in the least-evolved rhyolite in each suite. These variations can be accounted for by a systematic increase in degree of garnet-residual partial melting of amphibolite crust from east to west, correlating either with degree of extension with time along the Brothers fault zone, or with distance from the main axis of faulting. Porphyritic, calc-alkaline andesites and dacites erupted from at least six vents at Horsehead Mountain. Field relationships indicate a general decrease in age from southwest to northeast within the complex. At 15 Ma, calc-alkaline volcanism at Horsehead Mountain predates the age-progressive rhyolftes, and is instead part of an earlier phase of volcanism that produced the Steens and Columbia River flood basalts, along with several other caic-alkaline intermediate centers that are unrelated to subduction. Overlapping rare-earth element patterns of Horsehead Mountain intermediate rocks with those of Steens basalts precludes their derivation by fractionation from the broadly contemporaneous flood basalts. Close

• 82. [Article] The role of crustal and eruptive processes versus source variations in controlling the oxidation state of iron in Central Andean magmas

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier ...

  Citation × Citation Citation Abstract Copy Title: The role of crustal and eruptive processes versus source variations in controlling the oxidation state of iron in Central Andean magmas Author: de Silva, Shanaka, Grocke, Stephanie B., Kelley, Katherine A., Cottrell, Elizabeth To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/earth-and-planetary-science-letters Title: The role of crustal and eruptive processes versus source variations in controlling the oxidation state of iron in Central Andean magmas Author: de Silva, Shanaka, Grocke, Stephanie B., Kelley, Katherine A., Cottrell, Elizabeth To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/earth-and-planetary-science-letters Close

• 83. [Article] GrockeRoleCrustalEruptive.pdf

  Citation × Citation Citation Abstract Copy Title: GrockeRoleCrustalEruptive.pdf Author: de Silva, Shanaka, Grocke, Stephanie B., Kelley, Katherine A., Cottrell, Elizabeth Title: GrockeRoleCrustalEruptive.pdf Author: de Silva, Shanaka, Grocke, Stephanie B., Kelley, Katherine A., Cottrell, Elizabeth Close

• 84. [Article] GrockeRoleCrustalEruptiveAppendix A.pdf

  Citation × Citation Citation Abstract Copy Title: GrockeRoleCrustalEruptiveAppendix A.pdf Author: de Silva, Shanaka, Grocke, Stephanie B., Kelley, Katherine A., Cottrell, Elizabeth Title: GrockeRoleCrustalEruptiveAppendix A.pdf Author: de Silva, Shanaka, Grocke, Stephanie B., Kelley, Katherine A., Cottrell, Elizabeth Close

• 85. [Article] GrockeRoleCrustalEruptiveAppendixATable1-3.xlsx

  Citation × Citation Citation Abstract Copy Title: GrockeRoleCrustalEruptiveAppendixATable1-3.xlsx Author: de Silva, Shanaka, Grocke, Stephanie B., Kelley, Katherine A., Cottrell, Elizabeth Title: GrockeRoleCrustalEruptiveAppendixATable1-3.xlsx Author: de Silva, Shanaka, Grocke, Stephanie B., Kelley, Katherine A., Cottrell, Elizabeth Close

• 86. [Article] Deconvolving orbital surface waves for the source duration of large earthquakes and modeling the receiver functions for the earth structure beneath a broadband seismometer array in the Cascadia subduction zone

  Citation × Citation Citation Abstract Copy Title: Deconvolving orbital surface waves for the source duration of large earthquakes and modeling the receiver functions for the earth structure beneath a broadband seismometer array in the Cascadia subduction zone Author: Li, Xiao-qing, 1963- Title: Deconvolving orbital surface waves for the source duration of large earthquakes and modeling the receiver functions for the earth structure beneath a broadband seismometer array in the Cascadia subduction zone Author: Li, Xiao-qing, 1963- Close

• 87. [Article] Rhyolitic magmatism of the High Lava Plains and adjacent Northwest Basin and Range, Oregon : implications for the evolution of continental crust

  Understanding continental crust formation and modification is a fundamental and longstanding geologic problem. Influx of mantle-derived basaltic magma and partial melting of the crust are two ways to drive ...

  Citation × Citation Citation Abstract Copy Title: Rhyolitic magmatism of the High Lava Plains and adjacent Northwest Basin and Range, Oregon : implications for the evolution of continental crust Author: Ford, Mark T., 1973- Understanding continental crust formation and modification is a fundamental and longstanding geologic problem. Influx of mantle-derived basaltic magma and partial melting of the crust are two ways to drive crustal differentiation. This process results in a low density upper crust and denser, more refractory lower crust, creating significant and vastly different geochemical reservoirs over time. The High Lava Plains (HLP) and Northwestern Basin and Range (NWBR) in central and eastern Oregon provide an excellent example of intraplate volcanism where we can examine the beginnings of segregation of a relatively young, recently accreted crust. The origins of continental magmatism and its relationship to plate tectonics, especially away from the continental margins, are only slowly becoming revealed. The western United States is the most volcanically active part of North America during Cenozoic time, and this activity includes the enigmatic volcanism of the HLP and NWBR. Rhyolitic volcanism in the HLP and NWBR is age-progressive but in a direction that is nearly perpendicular to North American Plate motion. Despite being erupted through a similar crust and with a similar composition of mafic input, the HLP province is strongly bimodal (basalt-rhyolite) while the NWBR province exhibits a continuum of compositions. High silica rhyolites are commonplace in the HLP, with approximately a 1:1 ratio of rhyolite to basalt, even though the crust is comprised of mafic accreted terranes. Asthenospheric flow, mantle melting and crustal extension coupled with southwesterly North American plate motion explain the age-progressive volcanism of the HLP and NWBR. Differential asthenopheric counterflow and mantle upwelling created by the down-going Cascadia slab, coupled with transtensional stresses related to the rotation of the North American plate and Basin and Range extension, decreasing to the north, can produce the observed variations in rhyolite compositions and volumes in the two adjacent provinces. These differences are caused by fundamentally different petrogenetic processes that take place in the crust. In the HLP, an increase in mantle-derived magma flux into the lower crust has created low silica rhyolite via partial melt that separated, coalesced and rose buoyantly. This low silica rhyolite may erupt, solidify in the upper crust, or differentiate by fractional crystallization to produce high-iron, high-silica rhyolite containing an anhydrous phase assemblage. In the NWBR, a smaller flux of basaltic magma, coupled with greater transtension resulted in small crustal processing zones where fractional crystallization coupled with magma mixing and recharge created a wide range of compositions. Partial melting to form rhyolites was limited. These rhyolites have lower iron, and hydrous phases (biotite, amphibole) are common. These processes modify the crust in different ways, leaving a stratified crust in the HLP but a less modified crust in the NWBR. Recent geophysical and isotopic studies bear out these differences and allow for a unified, internally consistent model for both provinces, one that relies only on partial melt generation driven by current plate movements and do not require a mantle plume contribution. The bimodal volcanism of the HLP is a direct consequence of the processes that cause the gravitational differentiation of the continental crust into upper and lower units. The model for the HLP is generally applicable to other localities that have predominantly mafic crust and a similar balance of crustal transtension and mantle-derived basaltic flux. One such place is Iceland, which has strongly bimodal (basalt – rhyolite) volcanism. In areas where silicic crust has become substantially more mafic due to a high flux of intraplated basalts, such as in the bimodal Snake River Plain, the model is also applicable. Title: Rhyolitic magmatism of the High Lava Plains and adjacent Northwest Basin and Range, Oregon : implications for the evolution of continental crust Author: Ford, Mark T., 1973- Understanding continental crust formation and modification is a fundamental and longstanding geologic problem. Influx of mantle-derived basaltic magma and partial melting of the crust are two ways to drive crustal differentiation. This process results in a low density upper crust and denser, more refractory lower crust, creating significant and vastly different geochemical reservoirs over time. The High Lava Plains (HLP) and Northwestern Basin and Range (NWBR) in central and eastern Oregon provide an excellent example of intraplate volcanism where we can examine the beginnings of segregation of a relatively young, recently accreted crust. The origins of continental magmatism and its relationship to plate tectonics, especially away from the continental margins, are only slowly becoming revealed. The western United States is the most volcanically active part of North America during Cenozoic time, and this activity includes the enigmatic volcanism of the HLP and NWBR. Rhyolitic volcanism in the HLP and NWBR is age-progressive but in a direction that is nearly perpendicular to North American Plate motion. Despite being erupted through a similar crust and with a similar composition of mafic input, the HLP province is strongly bimodal (basalt-rhyolite) while the NWBR province exhibits a continuum of compositions. High silica rhyolites are commonplace in the HLP, with approximately a 1:1 ratio of rhyolite to basalt, even though the crust is comprised of mafic accreted terranes. Asthenospheric flow, mantle melting and crustal extension coupled with southwesterly North American plate motion explain the age-progressive volcanism of the HLP and NWBR. Differential asthenopheric counterflow and mantle upwelling created by the down-going Cascadia slab, coupled with transtensional stresses related to the rotation of the North American plate and Basin and Range extension, decreasing to the north, can produce the observed variations in rhyolite compositions and volumes in the two adjacent provinces. These differences are caused by fundamentally different petrogenetic processes that take place in the crust. In the HLP, an increase in mantle-derived magma flux into the lower crust has created low silica rhyolite via partial melt that separated, coalesced and rose buoyantly. This low silica rhyolite may erupt, solidify in the upper crust, or differentiate by fractional crystallization to produce high-iron, high-silica rhyolite containing an anhydrous phase assemblage. In the NWBR, a smaller flux of basaltic magma, coupled with greater transtension resulted in small crustal processing zones where fractional crystallization coupled with magma mixing and recharge created a wide range of compositions. Partial melting to form rhyolites was limited. These rhyolites have lower iron, and hydrous phases (biotite, amphibole) are common. These processes modify the crust in different ways, leaving a stratified crust in the HLP but a less modified crust in the NWBR. Recent geophysical and isotopic studies bear out these differences and allow for a unified, internally consistent model for both provinces, one that relies only on partial melt generation driven by current plate movements and do not require a mantle plume contribution. The bimodal volcanism of the HLP is a direct consequence of the processes that cause the gravitational differentiation of the continental crust into upper and lower units. The model for the HLP is generally applicable to other localities that have predominantly mafic crust and a similar balance of crustal transtension and mantle-derived basaltic flux. One such place is Iceland, which has strongly bimodal (basalt – rhyolite) volcanism. In areas where silicic crust has become substantially more mafic due to a high flux of intraplated basalts, such as in the bimodal Snake River Plain, the model is also applicable. Close

• 88. [Article] Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological ...

  Citation × Citation Citation Abstract Copy Title: Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot Author: Duncan, Robert, Haeussler, Peter, Friedman, Richard, Wells, Ray, Bukry, David, Pyle, Doug, Wooden, Joe To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological Society of America and can be found at: http://geosphere.gsapubs.org/. Title: Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot Author: Duncan, Robert, Haeussler, Peter, Friedman, Richard, Wells, Ray, Bukry, David, Pyle, Doug, Wooden, Joe To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological Society of America and can be found at: http://geosphere.gsapubs.org/. Close

• 89. [Article] Shake, rattle, and roll : awaking the visiting public's curiosity of geology via interpretation at Redwood National State Parks

  By researching aspects of the geology of Redwood National and State Parks (RNSP) and serving for two summers as a seasonal interpretive ranger, I have developed a training manual designed for fellow rangers. ...

  Citation × Citation Citation Abstract Copy Title: Shake, rattle, and roll : awaking the visiting public's curiosity of geology via interpretation at Redwood National State Parks Author: Natoli, Jennifer A. By researching aspects of the geology of Redwood National and State Parks (RNSP) and serving for two summers as a seasonal interpretive ranger, I have developed a training manual designed for fellow rangers. The descriptive nature of the manual, combined with its vivid illustrations, is designed to enable rangers of all backgrounds to present the park's geology to visitors in accurate, interactive, inspiring, and thought-provoking programs. To develop successful programs, the geological processes most appropriate for interpretation to RNSP visitors were identified. The geology of Northern California's RNSP is dynamic. The Cascadia Subduction Zone (CSZ), where the Gorda Plate dives beneath North America, impacts the stability of the region and raises concern for earthquakes and ensuing tsunamis. The ongoing subduction, including uplift of materials from the sea floor, is responsible for the dramatic landscape of RNSP, forming the Coast Range and its rugged coastline. The landscape in turn controls ecological variables. Without the Coast Range, the fog necessary to support the towering redwood forest would not exist. The fracturing of rock layers in the park enhances erosion and landsliding. Such relationships between geology and ecology encourage rangers to present programs with interdisciplinary themes. Geologic processes and their societal importance need to be emphasized for the benefit of RNSP's 400,000 annual visitors. The majority of interpretive park rangers have degrees in life sciences or humanities, and few have much formal training in geology. The manual provides the basic concepts and tools to encourage rangers of all backgrounds to interpret the geology of RNSP to visitors. Plate tectonics, for example, gives interpreters the background necessary to understand a variety of geological processes germane to RNSP, such as earthquakes and related tsunamis. Chapters are designed around themes directly relevant for RNSP, including interpretation, plate tectonics, rock types, geologic structures, earthquakes, tsunamis, and geologic history. Non-technical text accompanies photographs and other illustrations to convey geologic processes at many scales, ranging from individual water particles to worldwide earthquake distribution. Analogies to familiar daily life events are used to present scientific concepts, and suggestions for methods to demonstrate the processes to the public are included. The appendices are designed to help rangers prepare for interpretive programs and relate to specific audiences. They include summaries of the geologic processes relevant to questions commonly asked by visitors, geologic limericks, interpretive program outlines, as well as results of visitor surveys. This version, submitted as a thesis to Oregon State University, will be reviewed by RNSP staff and others, and then revised to become a concise geology training manual for rangers at RNSP. Title: Shake, rattle, and roll : awaking the visiting public's curiosity of geology via interpretation at Redwood National State Parks Author: Natoli, Jennifer A. By researching aspects of the geology of Redwood National and State Parks (RNSP) and serving for two summers as a seasonal interpretive ranger, I have developed a training manual designed for fellow rangers. The descriptive nature of the manual, combined with its vivid illustrations, is designed to enable rangers of all backgrounds to present the park's geology to visitors in accurate, interactive, inspiring, and thought-provoking programs. To develop successful programs, the geological processes most appropriate for interpretation to RNSP visitors were identified. The geology of Northern California's RNSP is dynamic. The Cascadia Subduction Zone (CSZ), where the Gorda Plate dives beneath North America, impacts the stability of the region and raises concern for earthquakes and ensuing tsunamis. The ongoing subduction, including uplift of materials from the sea floor, is responsible for the dramatic landscape of RNSP, forming the Coast Range and its rugged coastline. The landscape in turn controls ecological variables. Without the Coast Range, the fog necessary to support the towering redwood forest would not exist. The fracturing of rock layers in the park enhances erosion and landsliding. Such relationships between geology and ecology encourage rangers to present programs with interdisciplinary themes. Geologic processes and their societal importance need to be emphasized for the benefit of RNSP's 400,000 annual visitors. The majority of interpretive park rangers have degrees in life sciences or humanities, and few have much formal training in geology. The manual provides the basic concepts and tools to encourage rangers of all backgrounds to interpret the geology of RNSP to visitors. Plate tectonics, for example, gives interpreters the background necessary to understand a variety of geological processes germane to RNSP, such as earthquakes and related tsunamis. Chapters are designed around themes directly relevant for RNSP, including interpretation, plate tectonics, rock types, geologic structures, earthquakes, tsunamis, and geologic history. Non-technical text accompanies photographs and other illustrations to convey geologic processes at many scales, ranging from individual water particles to worldwide earthquake distribution. Analogies to familiar daily life events are used to present scientific concepts, and suggestions for methods to demonstrate the processes to the public are included. The appendices are designed to help rangers prepare for interpretive programs and relate to specific audiences. They include summaries of the geologic processes relevant to questions commonly asked by visitors, geologic limericks, interpretive program outlines, as well as results of visitor surveys. This version, submitted as a thesis to Oregon State University, will be reviewed by RNSP staff and others, and then revised to become a concise geology training manual for rangers at RNSP. Close

• 90. [Article] Subsurface densities & lithospheric flexure of the Himalayan foreland in Pakistan, interpreted from gravity data

  Gravity data along a N-S profile from Kohistan to the Punjab plain of Pakistan have been incorporated into recent interpretation of the gross structure of the foreland fold and thrust belt of the Himalaya. ...

  Citation × Citation Citation Abstract Copy Title: Subsurface densities & lithospheric flexure of the Himalayan foreland in Pakistan, interpreted from gravity data Author: Duroy, Yannick Gravity data along a N-S profile from Kohistan to the Punjab plain of Pakistan have been incorporated into recent interpretation of the gross structure of the foreland fold and thrust belt of the Himalaya. In northern Pakistan large deviations from Airy Isostatic equilibrium are observed. An excess of mass characterizes the northern Kohistan arc and a deficit of mass underlies a broad area extending from southern Kohistan to the Salt Range, while to the south a slight excess of mass seems to prevail in the region of the Sargodha ridge. This anomalous distribution of mass can be understood if the Indian elastic plate, which is assumed to overlie an inviscid fluid, is flexed down under the weight of both the overthrust mountains and the sediments eroded off the mountain and deposited in the foredeep basin. In many respects the intracontinental subduction of India beneath the Himalaya is similar to island arc formation, including the seismically active Sargodha ridge, an outer topographic rise analogous to the flexural bulge encountered seaward of oceanic trenches. Analysis of Bouguer gravity anomalies along a profile extending from the Sargodha ridge to the main mantle thrust (MMT) show that most of the negative-southward gravity gradient can be attributed to crustal thickening, while short wavelength anomalies are produced by lateral variation of density within the northward thickening sedimentary wedge. In the Sargodha ridge area, an additional contribution of about 25 mgals appears to be due to excess of mass at lower crustal or upper mantle levels. The Moho discontinuity is interpreted to bulge up beneath the Sargodha high, then gradually increase in dip from 1° to 3° beneath the Salt Range and Potwar Plateau (approximately equal to the change in dip of the basement surface). The Moho slope changes from upwardly convex to upwardly concave beneath southern Kohistan. Finally, north of the Main Mantle Thrust (MMT) it bends down again, but at a steeper angle of about 15°. Shorter wavelength anomalies superimposed on the regional gradient are modeled in terms of upper crustal density changes, including those due to: 1) offsets of the basement surface, 2) variable thickness of the Eocambrian evaporite sequence that forms the basal decollement, 3) thrusting and folding of relatively high density, older parts of the stratigraphic section to higher structural levels, particularly in the Salt range and northern Potwar plateau, and 4) thickening of the low density Neogene molasse sequence into the axis of the Soan Syncline, a structural depression between the Salt range and northern Potwar plateau. Subsurface densities of the overthrust wedge, as well as the definition of the shape of the top surface of the Indian plate interpreted from gravity, place bounds on the flexural rigidity of such a plate and the forces that deform it. In northern Pakistan the flexural rigidity of the elastic Indian plate (D = 4.0 x 10²³ Nm) is a factor of 10 smaller than the current values interpreted for the central and eastern Himalaya. Because of the small elastic thickness interpreted for the Indian plate in Pakistan (He [approximately] 30 km), the Bouguer gravity gradient is steeper than in the Himalaya of India. Moreover the maximum flexural stresses are concentrated within the crust which may account for the seismic activity of the Sargodha ridge and southern Kohistan. At the end of the Indian elastic plate (arbitrarily chosen at the MMT), a large positive vertical shear stress, S₀ = 9.2 x 10¹² N/m, is applied to account for the topographic load north of the MMT. In addition, to fit the gravity constraints it was necessary to apply a strong negative bending moment, M₀ = -0.85 x 10¹⁸ N, at the end of the plate. The negative bending moment is due to the combined effect of the northward migration of the Indian plate and the southward differential compressional force generated by the crustal rocks stacked beneath the northern Kohistan arc. Consequently, in southern Kohistan the surface of the Indian plate is concave. The upper portion of the elastic plate is therefore under compressional regime, while the lower portion is subject to extentional stress. High flexural stresses are probably the primary source of the Hazara seismic zone where incipient reverse faulting seems to take place. In contrast, the pronounced convexity developed along the flexural bulge can account for 1) tensional stress in the upper part of the Indian plate, large enough to produce basement normal faults interpreted beneath the Salt range and Sargodha ridge; and 2) compressional stress in the lower portion of the crust that cause the excess of mass and seismicity beneath the Sargodha Ridge. Title: Subsurface densities & lithospheric flexure of the Himalayan foreland in Pakistan, interpreted from gravity data Author: Duroy, Yannick Gravity data along a N-S profile from Kohistan to the Punjab plain of Pakistan have been incorporated into recent interpretation of the gross structure of the foreland fold and thrust belt of the Himalaya. In northern Pakistan large deviations from Airy Isostatic equilibrium are observed. An excess of mass characterizes the northern Kohistan arc and a deficit of mass underlies a broad area extending from southern Kohistan to the Salt Range, while to the south a slight excess of mass seems to prevail in the region of the Sargodha ridge. This anomalous distribution of mass can be understood if the Indian elastic plate, which is assumed to overlie an inviscid fluid, is flexed down under the weight of both the overthrust mountains and the sediments eroded off the mountain and deposited in the foredeep basin. In many respects the intracontinental subduction of India beneath the Himalaya is similar to island arc formation, including the seismically active Sargodha ridge, an outer topographic rise analogous to the flexural bulge encountered seaward of oceanic trenches. Analysis of Bouguer gravity anomalies along a profile extending from the Sargodha ridge to the main mantle thrust (MMT) show that most of the negative-southward gravity gradient can be attributed to crustal thickening, while short wavelength anomalies are produced by lateral variation of density within the northward thickening sedimentary wedge. In the Sargodha ridge area, an additional contribution of about 25 mgals appears to be due to excess of mass at lower crustal or upper mantle levels. The Moho discontinuity is interpreted to bulge up beneath the Sargodha high, then gradually increase in dip from 1° to 3° beneath the Salt Range and Potwar Plateau (approximately equal to the change in dip of the basement surface). The Moho slope changes from upwardly convex to upwardly concave beneath southern Kohistan. Finally, north of the Main Mantle Thrust (MMT) it bends down again, but at a steeper angle of about 15°. Shorter wavelength anomalies superimposed on the regional gradient are modeled in terms of upper crustal density changes, including those due to: 1) offsets of the basement surface, 2) variable thickness of the Eocambrian evaporite sequence that forms the basal decollement, 3) thrusting and folding of relatively high density, older parts of the stratigraphic section to higher structural levels, particularly in the Salt range and northern Potwar plateau, and 4) thickening of the low density Neogene molasse sequence into the axis of the Soan Syncline, a structural depression between the Salt range and northern Potwar plateau. Subsurface densities of the overthrust wedge, as well as the definition of the shape of the top surface of the Indian plate interpreted from gravity, place bounds on the flexural rigidity of such a plate and the forces that deform it. In northern Pakistan the flexural rigidity of the elastic Indian plate (D = 4.0 x 10²³ Nm) is a factor of 10 smaller than the current values interpreted for the central and eastern Himalaya. Because of the small elastic thickness interpreted for the Indian plate in Pakistan (He [approximately] 30 km), the Bouguer gravity gradient is steeper than in the Himalaya of India. Moreover the maximum flexural stresses are concentrated within the crust which may account for the seismic activity of the Sargodha ridge and southern Kohistan. At the end of the Indian elastic plate (arbitrarily chosen at the MMT), a large positive vertical shear stress, S₀ = 9.2 x 10¹² N/m, is applied to account for the topographic load north of the MMT. In addition, to fit the gravity constraints it was necessary to apply a strong negative bending moment, M₀ = -0.85 x 10¹⁸ N, at the end of the plate. The negative bending moment is due to the combined effect of the northward migration of the Indian plate and the southward differential compressional force generated by the crustal rocks stacked beneath the northern Kohistan arc. Consequently, in southern Kohistan the surface of the Indian plate is concave. The upper portion of the elastic plate is therefore under compressional regime, while the lower portion is subject to extentional stress. High flexural stresses are probably the primary source of the Hazara seismic zone where incipient reverse faulting seems to take place. In contrast, the pronounced convexity developed along the flexural bulge can account for 1) tensional stress in the upper part of the Indian plate, large enough to produce basement normal faults interpreted beneath the Salt range and Sargodha ridge; and 2) compressional stress in the lower portion of the crust that cause the excess of mass and seismicity beneath the Sargodha Ridge. Close

• 91. [Article] Case Study for Tsunami Design of Coastal Infrastructure: Spencer Creek Bridge, Oregon

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the American ...

  Citation × Citation Citation Abstract Copy Title: Case Study for Tsunami Design of Coastal Infrastructure: Spencer Creek Bridge, Oregon Author: Potisuk, Tanarat, Azadbakht, Mohsen, Wei, Yong, Yim, Solomon C., Nimmala, Seshu To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the American Society of Civil Engineers and can be found at: http://ascelibrary.org/loi/jbenf2. Title: Case Study for Tsunami Design of Coastal Infrastructure: Spencer Creek Bridge, Oregon Author: Potisuk, Tanarat, Azadbakht, Mohsen, Wei, Yong, Yim, Solomon C., Nimmala, Seshu To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the American Society of Civil Engineers and can be found at: http://ascelibrary.org/loi/jbenf2. Close

• 92. [Article] Past Methane Release Events and Environmental Conditions at the Upper Continental Slope of the South China Sea: Constraints by Seep Carbonates

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://www.springer.com/earth+sciences+and+geogra...

  Citation × Citation Citation Abstract Copy Title: Past Methane Release Events and Environmental Conditions at the Upper Continental Slope of the South China Sea: Constraints by Seep Carbonates Author: Han, Xiqiu, Suess, Erwin, Eisenhauer, Anton, Huang, Yongyang, Liebetrau, Volker This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://www.springer.com/earth+sciences+and+geography/geology/journal/531 Title: Past Methane Release Events and Environmental Conditions at the Upper Continental Slope of the South China Sea: Constraints by Seep Carbonates Author: Han, Xiqiu, Suess, Erwin, Eisenhauer, Anton, Huang, Yongyang, Liebetrau, Volker This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://www.springer.com/earth+sciences+and+geography/geology/journal/531 Close

• 93. [Article] Paleoenvironmental reconstruction of an active margin coast from the Pleistocene to the present : examples from southwestern Oregon

  This study illustrates geoarchaeological and paleoenvironmental approaches to the investigation of an active margin coastal setting and provides examples of how information gleaned through examination ...

  Citation × Citation Citation Abstract Copy Title: Paleoenvironmental reconstruction of an active margin coast from the Pleistocene to the present : examples from southwestern Oregon Author: Punke, Michele Leigh This study illustrates geoarchaeological and paleoenvironmental approaches to the investigation of an active margin coastal setting and provides examples of how information gleaned through examination of the stratigraphic record can reveal depositional signatures that provide insights into the geomorphic and tectonic forces active within coastal river basins. Three case studies from the southern Oregon coast illustrate the complex relationship between tectonics and geomorphic processes along an active margin coast such as Oregon's Cascadia subduction zone. This work illustrates that the differential preservation of late Pleistocene-age terrestrial deposits in Oregon's coastal landscape, and the early cultural sites they may contain, is not random but can be closely related to larger tectonogeomorphic processes operating at local and regional scales. Detailed subsurface investigation of one case study site, the lower Sixes River valley, reveals a complex history of depositional environment evolution in relation to geomorphic and tectonic forces. Litho- and biostratigraphic data sets are used to develop a depositional environment reconstruction for the lower Sixes River site through time. This reconstruction of the depositional environment from the late Pleistocene to the present indicates a transgressive evolution that differs from models of transgressive coastal facies and from other studied Northwest coast estuarine life histories. Factors such as eustatic sea level rise, regional and local tectonic alteration of the landscape, sediment supply, or valley morphology may have played roles in the creation and preservation of this atypical depositional sequence. Litho- and biostratigraphic evidence of six Cascadia subduction zone earthquakes younger than 6200 cal yr BP is recorded in a long sediment core from the Sixes River valley. All six of these events correlate with events previously reported for the area by Kelsey et al. (2002). At least five additional plate boundary earthquakes lowered tidal marshes and freshwater wetlands prior to 6200 cal yr BP. The presence within the lower Sixes River valley of an intertidal environment capable of recording Cascadia subduction zone earthquakes dating to the late Pleistocene and early Holocene has not been found at any other location on the Northwest coast. Title: Paleoenvironmental reconstruction of an active margin coast from the Pleistocene to the present : examples from southwestern Oregon Author: Punke, Michele Leigh This study illustrates geoarchaeological and paleoenvironmental approaches to the investigation of an active margin coastal setting and provides examples of how information gleaned through examination of the stratigraphic record can reveal depositional signatures that provide insights into the geomorphic and tectonic forces active within coastal river basins. Three case studies from the southern Oregon coast illustrate the complex relationship between tectonics and geomorphic processes along an active margin coast such as Oregon's Cascadia subduction zone. This work illustrates that the differential preservation of late Pleistocene-age terrestrial deposits in Oregon's coastal landscape, and the early cultural sites they may contain, is not random but can be closely related to larger tectonogeomorphic processes operating at local and regional scales. Detailed subsurface investigation of one case study site, the lower Sixes River valley, reveals a complex history of depositional environment evolution in relation to geomorphic and tectonic forces. Litho- and biostratigraphic data sets are used to develop a depositional environment reconstruction for the lower Sixes River site through time. This reconstruction of the depositional environment from the late Pleistocene to the present indicates a transgressive evolution that differs from models of transgressive coastal facies and from other studied Northwest coast estuarine life histories. Factors such as eustatic sea level rise, regional and local tectonic alteration of the landscape, sediment supply, or valley morphology may have played roles in the creation and preservation of this atypical depositional sequence. Litho- and biostratigraphic evidence of six Cascadia subduction zone earthquakes younger than 6200 cal yr BP is recorded in a long sediment core from the Sixes River valley. All six of these events correlate with events previously reported for the area by Kelsey et al. (2002). At least five additional plate boundary earthquakes lowered tidal marshes and freshwater wetlands prior to 6200 cal yr BP. The presence within the lower Sixes River valley of an intertidal environment capable of recording Cascadia subduction zone earthquakes dating to the late Pleistocene and early Holocene has not been found at any other location on the Northwest coast. Close

• 94. [Article] The case for NE-SW extension in northeast Oregon

  A zone of diffuse deformation -600 km-wide extending from northern California to Washington has developed resulting from the oblique subduction of the Juan de Fuca plate beneath North America, and the ...

  Citation × Citation Citation Abstract Copy Title: The case for NE-SW extension in northeast Oregon Author: Essman, Jim E. A zone of diffuse deformation -600 km-wide extending from northern California to Washington has developed resulting from the oblique subduction of the Juan de Fuca plate beneath North America, and the northwestward migration of the Pacific plate. This zone is marked by a change in structural style from transtension in the southern Oregon and western Nevada to transpression in southern and western Washington. The transition occurs across a relatively inactive zone in northeastern Oregon. New geologic mapping near the northern edge of this transitional zone suggests that extensional deformation persists into northeastern Oregon. The study area on the Oregon-Idaho border, is a complex zone characterized by NNWtrending primarily sinistral-oblique normal faults linking the NW-trending Halfway and Sturgill Peak (both down to the NE) normal faults to the NW and SE, respectively. The Halfway fault, -20 km-long - 730 m dip-slip separation, marks the southern boundary of a half-graben; whereas the Sturgill Peak fault, - 10 to 15 km long and not associated with a half-graben, has a minimum dip-slip separation of - 660 m. In contrast, the transfer zone informally named the Powder River Peninsula Fault Zone, or PRPFZ, houses numerous -NNW-striking, 2 to 3 km-long normal and sinistral-oblique normal faults with dip-slip separations of < 130 m. Evidence of late Pleistocene-Holocene deformation within the transfer zone is found in at least four places, and at two of those involves sinistral-oblique normal faults (-10-15 m vertical separation on a bedrock scarp) cutting late Pleistocene Bonneville flood gravels, -14 ka, with flood gravels both entrained in the fault plane and interbedded with Holocene colluvium implying significant activity in the late Pleistocene and possibly the early Holocene. Additionally, one fault in the PRPFZ cuts Holocene (?) soils/clays and deforms Pleistocene ash beds. Slip rates calculated from slickenlines and separations in the PRPFZ range from 0.01 mm/yr to possibly as high as 2.8 mm/yr to. This detailed slip data for the PRPFZ can be used as a proxy for the more regional deformational styles. Although the Halfway and Sturgill Peak faults have been interpreted to represent the southeastern extension of the Olympic-Wallowa Lineament (OWL), the tectonic and structural significance of the OWL remains poorly understood. It is suggested here that these structures reflect the continuation of Basinand-Range style deformation into northeastern Oregon, and western Idaho, and any connection to the OWL to be circumstantial. Furthermore, the presence of these structures poses a potential seismic hazard to local hydroelectric facilities. Title: The case for NE-SW extension in northeast Oregon Author: Essman, Jim E. A zone of diffuse deformation -600 km-wide extending from northern California to Washington has developed resulting from the oblique subduction of the Juan de Fuca plate beneath North America, and the northwestward migration of the Pacific plate. This zone is marked by a change in structural style from transtension in the southern Oregon and western Nevada to transpression in southern and western Washington. The transition occurs across a relatively inactive zone in northeastern Oregon. New geologic mapping near the northern edge of this transitional zone suggests that extensional deformation persists into northeastern Oregon. The study area on the Oregon-Idaho border, is a complex zone characterized by NNWtrending primarily sinistral-oblique normal faults linking the NW-trending Halfway and Sturgill Peak (both down to the NE) normal faults to the NW and SE, respectively. The Halfway fault, -20 km-long - 730 m dip-slip separation, marks the southern boundary of a half-graben; whereas the Sturgill Peak fault, - 10 to 15 km long and not associated with a half-graben, has a minimum dip-slip separation of - 660 m. In contrast, the transfer zone informally named the Powder River Peninsula Fault Zone, or PRPFZ, houses numerous -NNW-striking, 2 to 3 km-long normal and sinistral-oblique normal faults with dip-slip separations of < 130 m. Evidence of late Pleistocene-Holocene deformation within the transfer zone is found in at least four places, and at two of those involves sinistral-oblique normal faults (-10-15 m vertical separation on a bedrock scarp) cutting late Pleistocene Bonneville flood gravels, -14 ka, with flood gravels both entrained in the fault plane and interbedded with Holocene colluvium implying significant activity in the late Pleistocene and possibly the early Holocene. Additionally, one fault in the PRPFZ cuts Holocene (?) soils/clays and deforms Pleistocene ash beds. Slip rates calculated from slickenlines and separations in the PRPFZ range from 0.01 mm/yr to possibly as high as 2.8 mm/yr to. This detailed slip data for the PRPFZ can be used as a proxy for the more regional deformational styles. Although the Halfway and Sturgill Peak faults have been interpreted to represent the southeastern extension of the Olympic-Wallowa Lineament (OWL), the tectonic and structural significance of the OWL remains poorly understood. It is suggested here that these structures reflect the continuation of Basinand-Range style deformation into northeastern Oregon, and western Idaho, and any connection to the OWL to be circumstantial. Furthermore, the presence of these structures poses a potential seismic hazard to local hydroelectric facilities. Close

• 95. [Article] Snow Peak, OR: late Miocene to early Pliocene volcanism in the central Cascadia forearc

  Snow Peak is a voluminous shield volcano located ~50 km west of the axis of the modern Cascade arc. A previously published K-Ar age estimate indicates that the Snow Peak lavas are ~3 Ma. Subsequently, ...

  Citation × Citation Citation Abstract Copy Title: Snow Peak, OR: late Miocene to early Pliocene volcanism in the central Cascadia forearc Author: Hatfield, Ashley K. Snow Peak is a voluminous shield volcano located ~50 km west of the axis of the modern Cascade arc. A previously published K-Ar age estimate indicates that the Snow Peak lavas are ~3 Ma. Subsequently, the preliminary research framework for studying the Snow Peak lavas focused on constraining the petrogenesis of the primitive lava compositions, thereby addressing the chemical and thermal structure of the Cascadia forearc mantle. However, ⁴⁰Ar/³⁹Ar age dating conducted for this study indicates that the Snow Peak lavas are ~5.5 – 6 Ma. Consequently, the research framework undertaken for this thesis focused on constraining the petrogenetic pathway of the Snow Peak lavas, thereby addressing the volcano-tectonic development of the early High Cascades. ⁴⁰Ar/³⁹Ar age results for the spatial range of the Snow Peak volcanic center indicate that the volcano formed between ~5.5 and 6 Ma. Whole-rock major and trace element geochemical results indicate that Snow Peak is a monogenetic, basaltic volcanic center that unconformably overlies the Western Cascades. Petrographic analysis coupled with end-member mineral chemistry results indicate that phenocryst phases consist of olivine, pyroxene, and plagioclase. Decompression crystal fractionation of this phase assemblage explains the observed liquid line of descent. Phase equilibria modeling in COMAGMAT of a selected primitive, and a selected daughter sample, indicate that differentiation of the Snow Peak lavas began ~8-10 kb, and ~1150°C – 1200°C, and the Snow Peak daughter formed ~1-2 kb and ~1050°C – 1150°C. A plagioclase hygrometer indicates that the Snow Peak lavas contain ~2 wt % H₂O. These results are consistent with melting of moderately enriched mantle and addition of a relatively small amount of LILE-enriched slab-derived material. The timing of volcanism at Snow Peak correlates to the development of an intra-arc rift, marked by the eruption of voluminous mafic lava flows, such as the Deschutes Formation, and early Mt. Jefferson basalts. Mafic underplating may have played a greater role in Cascadia volcanism during such periods of intra-arc rifting, and such an extensional tectonic setting could facilitate the eruption of basaltic lavas. Additionally, Snow Peak aligns with the NW-trending Brother's Fault zone, although the Snow Peak center lies on the western side of the arc axis. Snow Peak magma may have formed in response to decompression associated with uplift along the Brother's Fault zone, with a fluid flux from the downgoing slab. Title: Snow Peak, OR: late Miocene to early Pliocene volcanism in the central Cascadia forearc Author: Hatfield, Ashley K. Snow Peak is a voluminous shield volcano located ~50 km west of the axis of the modern Cascade arc. A previously published K-Ar age estimate indicates that the Snow Peak lavas are ~3 Ma. Subsequently, the preliminary research framework for studying the Snow Peak lavas focused on constraining the petrogenesis of the primitive lava compositions, thereby addressing the chemical and thermal structure of the Cascadia forearc mantle. However, ⁴⁰Ar/³⁹Ar age dating conducted for this study indicates that the Snow Peak lavas are ~5.5 – 6 Ma. Consequently, the research framework undertaken for this thesis focused on constraining the petrogenetic pathway of the Snow Peak lavas, thereby addressing the volcano-tectonic development of the early High Cascades. ⁴⁰Ar/³⁹Ar age results for the spatial range of the Snow Peak volcanic center indicate that the volcano formed between ~5.5 and 6 Ma. Whole-rock major and trace element geochemical results indicate that Snow Peak is a monogenetic, basaltic volcanic center that unconformably overlies the Western Cascades. Petrographic analysis coupled with end-member mineral chemistry results indicate that phenocryst phases consist of olivine, pyroxene, and plagioclase. Decompression crystal fractionation of this phase assemblage explains the observed liquid line of descent. Phase equilibria modeling in COMAGMAT of a selected primitive, and a selected daughter sample, indicate that differentiation of the Snow Peak lavas began ~8-10 kb, and ~1150°C – 1200°C, and the Snow Peak daughter formed ~1-2 kb and ~1050°C – 1150°C. A plagioclase hygrometer indicates that the Snow Peak lavas contain ~2 wt % H₂O. These results are consistent with melting of moderately enriched mantle and addition of a relatively small amount of LILE-enriched slab-derived material. The timing of volcanism at Snow Peak correlates to the development of an intra-arc rift, marked by the eruption of voluminous mafic lava flows, such as the Deschutes Formation, and early Mt. Jefferson basalts. Mafic underplating may have played a greater role in Cascadia volcanism during such periods of intra-arc rifting, and such an extensional tectonic setting could facilitate the eruption of basaltic lavas. Additionally, Snow Peak aligns with the NW-trending Brother's Fault zone, although the Snow Peak center lies on the western side of the arc axis. Snow Peak magma may have formed in response to decompression associated with uplift along the Brother's Fault zone, with a fluid flux from the downgoing slab. Close

• 96. [Article] Fluid budgets along the northern Hikurangi subduction margin, New Zealand: the effect of a subducting seamount on fluid pressure

  ©The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society. The published article can be found at: http://gji.oxfordjournals.org/content/202/1/277

  Citation × Citation Citation Abstract Copy Title: Fluid budgets along the northern Hikurangi subduction margin, New Zealand: the effect of a subducting seamount on fluid pressure Author: Fagereng, Åke, Harris, Rob, et al., Ellis, Susan, Barker, Dan ©The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society. The published article can be found at: http://gji.oxfordjournals.org/content/202/1/277 Title: Fluid budgets along the northern Hikurangi subduction margin, New Zealand: the effect of a subducting seamount on fluid pressure Author: Fagereng, Åke, Harris, Rob, et al., Ellis, Susan, Barker, Dan ©The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society. The published article can be found at: http://gji.oxfordjournals.org/content/202/1/277 Close

• 97. [Article] HarrisRobCEOASFluidBudgetsAlong.pdf

  Citation × Citation Citation Abstract Copy Title: HarrisRobCEOASFluidBudgetsAlong.pdf Author: Fagereng, Åke, Harris, Rob, Barker, Dan, Ellis, Susan, et al. Title: HarrisRobCEOASFluidBudgetsAlong.pdf Author: Fagereng, Åke, Harris, Rob, Barker, Dan, Ellis, Susan, et al. Close

• 98. [Article] HarrisRobCEOASFluidBudgetsAlongSupportingInformationSup1-4.pdf

  Citation × Citation Citation Abstract Copy Title: HarrisRobCEOASFluidBudgetsAlongSupportingInformationSup1-4.pdf Author: Fagereng, Åke, Harris, Rob, et al., Ellis, Susan, Barker, Dan Title: HarrisRobCEOASFluidBudgetsAlongSupportingInformationSup1-4.pdf Author: Fagereng, Åke, Harris, Rob, et al., Ellis, Susan, Barker, Dan Close

• 99. [Article] A synthesis of heat flow determinations and thermal modeling along the Nankai Trough, Japan

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-9356.

  Citation × Citation Citation Abstract Copy Title: A synthesis of heat flow determinations and thermal modeling along the Nankai Trough, Japan Author: Kinoshita, Masataka, Hamamoto, Hideki, Yamano, Makoto, Spinelli, Glenn, Harris, Robert, Ashi, Juichiro This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-9356. Title: A synthesis of heat flow determinations and thermal modeling along the Nankai Trough, Japan Author: Kinoshita, Masataka, Hamamoto, Hideki, Yamano, Makoto, Spinelli, Glenn, Harris, Robert, Ashi, Juichiro This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-9356. Close

• 100. [Article] The Cascadia Initiative: A Sea Change In Seismological Studies of Subduction Zones

  This is the publisher’s final pdf. The published article is copyrighted by the Oceanography Society and can be found at: http://www.tos.org/oceanography/index.html.

  Citation × Citation Citation Abstract Copy Title: The Cascadia Initiative: A Sea Change In Seismological Studies of Subduction Zones Author: Toomey, Douglas R., Dziak, Robert P., Allen, Richard M., et al., Tréhu, Anne M., Barclay, Andrew H. This is the publisher’s final pdf. The published article is copyrighted by the Oceanography Society and can be found at: http://www.tos.org/oceanography/index.html. Title: The Cascadia Initiative: A Sea Change In Seismological Studies of Subduction Zones Author: Toomey, Douglas R., Dziak, Robert P., Allen, Richard M., et al., Tréhu, Anne M., Barclay, Andrew H. This is the publisher’s final pdf. The published article is copyrighted by the Oceanography Society and can be found at: http://www.tos.org/oceanography/index.html. Close