Poster #252, Earthquake Forecasting and Predictability (EFP)
Re-evaluation of the role of static stress triggering for aftershocks following the Ridgecrest, California earthquake sequence considering receiver plane uncertainty
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Poster Presentation
2021 SCEC Annual Meeting, Poster #252, SCEC Contribution #11287 VIEW PDF
cts a higher percentage (96%) of triggered aftershocks relative to that predicted when using nominal aftershock rupture planes (65-78%), independent of how focal plane ambiguity is resolved. Further, observed aftershock focal planes appear to be statistically distinct from OOPs. Observed rupture planes, at least for larger magnitude events (M>3), appear to align more closely with pre-existing structure. Accounting for observational uncertainty associated with focal plane ambiguity, rupture plane orientation, and, to second order, aftershock locations permits a larger percentage of aftershocks to have potentially been triggered by static stress change, such that we cannot exclude static stress as the triggering mechanism for nearly all of the aftershocks considered in our study, particularly those further than 5 km from the modelled rupture planes. Dynamic stresses, afterslip, pore fluids, and other sources of unresolved small-scale heterogeneity in the post-mainshock stress field may also contribute appreciably to the occurrence of aftershocks closer to the mainshock.
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