Implications of Receiver Plane Uncertainty for the Static Stress Triggering Hypothesis

Static stress transfer from major earthquakes is commonly invoked as the primary mechanism for triggering aftershocks, but evaluating this depends on aftershock rupture plane orientations and hypocenter locations, which are often subject to significant observational uncertainty. We evaluate static change an unusually large data set comprising hundreds thousands of aftershocks following 1997 Umbria-Marche, 2009 L’Aquila (Italy), 2019 Ridgecrest (California) earthquake sequences. compare failure resolved focal planes that optimally oriented (OOPs) in regional perturbed field. Like previous studies, we find OOPs overpredicts percentage (>70%) triggered relative predicted observed (∼50%–65%) mechanisms solutions, independent how nodal ambiguity resolved. Further, appear statistically different OOPs. Observed planes, at least larger magnitude events (M > 3), align more closely with pre-existing tectonic structures. The inferred uncertainty associated ambiguity, orientation, and, second order, hypocentral location yields a broad range potentially by changes, ranging slightly better than random chance nearly any promoted, particularly those further 5 km causative fault. Dynamic stresses, afterslip, pore fluids, other sources unresolved small-scale heterogeneity post-mainshock field may also contribute appreciably occurrence closer mainshock.