An improved space-time ETAS model for inverting the rupture geometry from seismicity triggering

Abstract:

This study incorporates the rupture geometry of big earthquakes in the formulation of the
Epidemic-Type Aftershock Sequence (ETAS) model, which is a point process model widely applied in the
study of spatiotemporal seismicity, rather than regarding every earthquake occurring at a point in space and
time. We apply the new model to the catalog from Sichuan province, China, between 1990 and 2013, during
which the Wenchuan Mw7.9 earthquake occurred in May 2008. Our results show that the modified model
has better performance in both data fitting and aftershock simulation, confirming that the elliptic aftershock
zone is caused by the superposition of the isotropic triggering effect from each patch of the rupture zone.
Moreover, using the technique of stochastic reconstruction, we inverted the fault geometry and verified
that direct aftershocks of the main shock more likely occur in the transitive parts from high-slip parts to
low/median slip parts of the main shock fault area.