Numerical simulation of afterslips and slow slip events that occurred in the same area in Hyuga-nada of southwest Japan

Abstract

We propose a model of numerical simulation for the coexistence of afterslip for ∼M7 earthquake and slow slip events in the Hyuga-nada region of Japan that incorporates 3-D geometry of the Philippine Sea Plate. Coseismic slip events, recurrence of slow slip events and afterslip are qualitatively reproduced using the composite law, which is a type of rate- and state-dependent friction law with higher cut-off velocity. In addition, characteristic slip distances in the area are larger than those in other seismic source areas. In our simulation, afterslip, which occurred at the velocity-weakening regime, triggered an aseismic transient event. After the termination of this event, spontaneous slow slip events repeatedly occurred in the same area. After a similar event sequence was repeated, another afterslip occurrence triggered a larger coseismic slip in a wide area including that of the slow slip events. Following this coseismic slip, the aseismic slip area was locked until the next afterslip propagation, which triggered an aseismic transient event. These results suggest that detailed observation of spatial and temporal distribution within the area of aseismic slip may indicate the potential of recurring slow slip events and future large earthquakes. © 2012 The Authors Geophysical Journal International © 2012 RAS.