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• 1. [Article] Does hydrologic circulation mask frictional heat on faults after large earthquakes?

  Knowledge of frictional resistance along faults is important for understanding the mechanics of earthquakes and faulting. The clearest in situ measure of fault friction potentially comes from temperature ...

  Citation × Citation Citation Abstract Copy Title: Does hydrologic circulation mask frictional heat on faults after large earthquakes? Author: Brodsky, Emily E., Saffer, Demian M., Fulton, Patrick M., Harris, Robert N. Knowledge of frictional resistance along faults is important for understanding the mechanics of earthquakes and faulting. The clearest in situ measure of fault friction potentially comes from temperature measurements in boreholes crossing fault zones within a few years of rupture. However, large temperature signals from frictional heating on faults have not been observed. Unambiguously interpreting the coseismic frictional resistance from small thermal perturbations observed in borehole temperature profiles requires assessing the impact of other potentially confounding thermal processes. We address several issues associated with quantifying the temperature signal of frictional heating including transient fluid flow associated with the earthquake, thermal disturbance caused by borehole drilling, and heterogeneous thermal physical rock properties. Transient fluid flow is investigated using a two‐dimensional coupled fluid flow and heat transport model to evaluate the temperature field following an earthquake. Simulations for a range of realistic permeability, frictional heating, and pore pressure scenarios show that high permeabilities (>10−14 m2) are necessary for significant advection within the several years after an earthquake and suggest that transient fluid flow is unlikely to mask frictional heat anomalies. We illustrate how disturbances from circulating fluids during drilling diffuse quickly leaving a robust signature of frictional heating. Finally, we discuss the utility of repeated borehole temperature profiles for discriminating between different interpretations of thermal perturbations. Our results suggest that temperature anomalies from even low friction should be detectable at depths >1 km 1 to 2 years after a large earthquake and that interpretations of low friction from existing data are likely robust. Title: Does hydrologic circulation mask frictional heat on faults after large earthquakes? Author: Brodsky, Emily E., Saffer, Demian M., Fulton, Patrick M., Harris, Robert N. Knowledge of frictional resistance along faults is important for understanding the mechanics of earthquakes and faulting. The clearest in situ measure of fault friction potentially comes from temperature measurements in boreholes crossing fault zones within a few years of rupture. However, large temperature signals from frictional heating on faults have not been observed. Unambiguously interpreting the coseismic frictional resistance from small thermal perturbations observed in borehole temperature profiles requires assessing the impact of other potentially confounding thermal processes. We address several issues associated with quantifying the temperature signal of frictional heating including transient fluid flow associated with the earthquake, thermal disturbance caused by borehole drilling, and heterogeneous thermal physical rock properties. Transient fluid flow is investigated using a two‐dimensional coupled fluid flow and heat transport model to evaluate the temperature field following an earthquake. Simulations for a range of realistic permeability, frictional heating, and pore pressure scenarios show that high permeabilities (>10−14 m2) are necessary for significant advection within the several years after an earthquake and suggest that transient fluid flow is unlikely to mask frictional heat anomalies. We illustrate how disturbances from circulating fluids during drilling diffuse quickly leaving a robust signature of frictional heating. Finally, we discuss the utility of repeated borehole temperature profiles for discriminating between different interpretations of thermal perturbations. Our results suggest that temperature anomalies from even low friction should be detectable at depths >1 km 1 to 2 years after a large earthquake and that interpretations of low friction from existing data are likely robust. Close

• 2. [Article] Thermal conductivities, thermal diffusivities, and volumetric heat capacities of core samples obtained from the Japan Trench Fast Drilling Project (JFAST)

  This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Springer. The published article can be found at: http://www.earth-planets-space.com/.

  Citation × Citation Citation Abstract Copy Title: Thermal conductivities, thermal diffusivities, and volumetric heat capacities of core samples obtained from the Japan Trench Fast Drilling Project (JFAST) Author: Kinoshita, Masataka, Tanikawa, Wataru, Lin, Weiren, Tadai, Osamu, Matsubayashi, Osamu, Fulton, Patrick M., Harris, Robert N. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Springer. The published article can be found at: http://www.earth-planets-space.com/. Title: Thermal conductivities, thermal diffusivities, and volumetric heat capacities of core samples obtained from the Japan Trench Fast Drilling Project (JFAST) Author: Kinoshita, Masataka, Tanikawa, Wataru, Lin, Weiren, Tadai, Osamu, Matsubayashi, Osamu, Fulton, Patrick M., Harris, Robert N. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Springer. The published article can be found at: http://www.earth-planets-space.com/. Close