[SCG53-P25] Modeling slow-slip events and their triggering by the Kaikoura earthquake along the Hikurangi subduction plate interface
Keywords:Hikurangi subduction zone, Slow-slip events, Kaikoura earthquake
We model SSEs along the Hikurangi subduction zone using a rate- and state-dependent friction law with a cutoff velocity to establish an evolution effect. First, we reproduce short- and long-term SSEs by setting the effective stress and critical displacement (Dc) to approximately 1.0 MPa and 0.15 cm, respectively, for shallow, short-term SSEs and to approximately 5.0 MPa and 1.0 cm, respectively, for deep, long-term SSEs. We show that the long-term SSE in southern Hikurangi could have been triggered by static stress increases resulting from the Kaikoura earthquake.
We also try to model shallow SSEs caused by dynamic triggering. For simplicity, we consider only the zone of shallow SSEs, and we simulate cycles of these events. We use large values of Dc and effective stress for the southern section to reproduce the longer recurrence intervals. Then, we give a stress perturbation that is a sine function of time and that propagates from south to north. Just after the perturbation, the slip velocity increases, and then slips continue to occur. In the southern section in particular, a triggered SSE can continue for a long duration, which is consistent with the observations. Our results suggest that the southern section of the shallow SSE zone has a larger fracture energy (i.e., larger Dc and effective stress) than the northern section has.