Dynamic fault rupture processes of moderate-size earthquakes inferred from the results of kinematic waveform inversion

Several attempts have been made recently to infer the dynamic rupture processes of moderate-size earthquakes from kinematic waveform inversion and dynamic crack inversion. These studies have revealed a quite heterogeneous distribution of dynamic stress drop and relative fault strength over the fault for most earthquakes. In two strike-slip California earthquakes, negative stress drop has been identified in a shallow section of the fault, suggesting the possible existence of a zone of velocity-strengthening frictions. The dynamic models yielded quite short rise times comparable to those inferred from kinematic modelling of observed waveforms. The short slip durations for these earthquakes may probably be attributed to shorter length scale of fault segmentation due to the heterogeneities of shear stress and fault strength.