Evan T. Hirakawa and Shuo Ma’s poster presentation at the 2014 SCEC Annual Meeting.
|Dynamic Compaction as a Simple Mechanism for Fault Zone Weakening
|Evan T. Hirakawa and Shuo Ma|
Elevated pore fluid pressures have long been thought to contribute to the apparent weakness of large plate bounding faults such as the San Andreas Fault. Sleep and Blanpied (1992) propose a mechanism in which compaction during interseismic creep reduces available pore space and hence increases fluid pressure. Assuming that the fault zone is not fully compacted during the interseismic period, we invoke a similar concept in this study, however in this case the compaction process occurs dynamically via the stresses associated with earthquake rupture. Microstructural analysis of fault zone rocks reveals intragranular fragmentation that is developed dynamically (e.g. Rempe et al., 2009) and is consistent with the style of fracture observed in individual quartz grains during bulk compaction (Chester et al., 2004), which thus lends some justification to our proposed mechanism.
|Abstract for a poster presentation at the 2014 SCEC Annual Meeting.|