Rupture history of 2014 Mw 6.0 South Napa earthquake inferred from near‐fault strong motion data and its impact to the practice of ground strong motion prediction

Abstract

AbstractThe spatiotemporal rupture history of the 2014 South Napa earthquake is constrained using near‐fault strong motion records. An aggressive source parameterization with 1372 subfaults is adopted to match the signals in the transverse components up to 4 Hz. The result reveals that the rupture of the Napa earthquake initiated at a depth of 9.84 km and propagated mainly to north‐northwest (NNW) and updip on a 13 km long fault patch. A gradual increase in average rise time when the rupture propagates to shallower depth is observed. However, it is the rupture of a small (Mw 4.9), isolated, and high stress drop fault patch that excited the largest ground acceleration at stations south of the epicenter. Such fine‐scale rupture heterogeneity shall be considered during seismic hazard analysis.