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Spatiotemporal Variations in Shallow Damage Zone Mechanisms Along the Southern Elsinore Fault

Description: 

Evidence from laboratory earthquake experiments, observational seismology, and theoretical fracture mechanics suggest that inelastic off-fault deformation should be more extensive for large earthquakes than small events. This begs the question of whether or not we can determine the seismic potential of active fault zones by examining properties of their damage zones. Faults accrue off-fault damage throughout their evolution via a number of different mechanisms that can be loosely grouped into quasi-static mechanisms related to slow, long-term processes involved in fault growth and deformation over many seismic cycles, to dynamic mechanisms related to earthquake rupture. We have studied the damage zones in outcrops of similar rocks along three active faults (listed in order of increasing historical or paleoseismic earthquake magnitude) – the Superstition Hills Fault, the Elsinore Fault, and the southern San Andreas Fault – in order to test the hypotheses that (A) we can identify fault damage structures uniquely related to dynamic rupture, and (B) that these structures hold information about the seismic potential of the fault. Here, we focus on results from the Elsinore Fault, where we describe strain partitioning in the damage zone between purely volumetric mechanisms and primarily deviatoric mechanisms that operate at different spatial scales across the damage zone. We argue that the volumetric mechanisms are uniquely dynamic in nature, whereas the deviatoric mechanisms are likely quasi-static. Finally, we compare and contrast these observations with preliminary work along the Superstition Hills fault and the Coachella segment of the southern San Andreas Fault.

Session: Above the Seismogenic Zone: Fault Damage and Healing in the Shallow Crust

Type: Oral

Date: 4/19/2023

Presentation Time: 04:45 PM (local time)

Presenting Author: Aidan Fullriede

Student Presenter: Yes

Invited Presentation: 

Authors