题 目:Seismic Imaging of Fault Zone Processes on the San Andreas Fault near Parkfield
报告内容:
Earthquakes are caused by the sudden release of stresses along faults. Plate tectonics describes the long-term strain accumulation, but the specifics of stress release—what ultimately leads to fault failure and how failure manifests itself (as a small or large earthquake, as aseismic slip, or as non-volcanic tremor)- are still not well understood. Current models of earthquake recurrence that assume constant loading rates and fixed fault strength are far too simplistic to describe exciting new observations of time-varying fault behavior. From among many examples, we present a few recent discoveries of temporal changes in fault zone processes near Parkfield, CA. These discoveries were made possible by advanced borehole seismic recordings from the High-Resolution Seismic Network and the San Andreas Fault Observatory at Depth (SAFOD) drill holes.