Abstract

The spatiotemporal behavior of aftershocks is one of the fundamental problems for seismology. The Big Bear sequence is among the best‐studied Mw 5 earthquake sequences available to seismologists because the relocated aftershocks lined up with complex subvertical faults on the surface, suggesting that the relocated earthquake locations are accurate to within tens of meters. Previously, Chi and Hauksson (2006) showed that most of these aftershocks fall into the advance region of the Coulomb stress transfer region. However, it will be helpful to analyze timing of the aftershocks. Here, I tested two currently available time‐dependent hydroseismology models and found both methods gave consistent and reasonable crustal permeability results. The fact that the aftershocks follow the diffusion law suggests that at least some of the aftershocks were not triggered solely by the very small Coulomb stress transfer, but also were helped by the reduced effective stress due to the higher pore pressure diffused away from the mainshock region. On the other hand, the diffusion alone would not have been able to trigger the aftershock, based on the good fit of the Coulomb stress transfer advance region to the aftershock distribution. A hypothesis that combines both Coulomb stress transfer and diffusion analyses will be necessary in the future to better study the aftershock sequence.

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