Effect of a large outer rise earthquake on seismic cycles of interplate earthquakes: A model study

A numerical simulation of the sliding process of a plate interface is performed to investigate the effect of stress perturbation due to a large outer rise earthquake on seismic cycles of large interplate earthquakes in a subduction zone. A two-dimensional model of uniform elastic half-space is set up for repeatedly occurring large interplate earthquakes by assuming that the frictional stress on the plate interface obeys a rate- and state-dependent friction law derived from laboratory experiments. An increase in shear stress on a shallow part of the plate interface due to a tensional outer rise earthquake promotes aseismic sliding on the shallower aseismic zone of the plate interface. This aseismic sliding advances the occurrence time of the next interplate earthquake. On the other hand, a compressional outer rise earthquake tends to delay the occurrence time of the next interplate earthquake. The magnitude of time advance or delay of the next interplate earthquake depends on the time of the outer rise earthquake in a seismic cycle due mainly to the complex behavior in propagation of aseismic sliding governed By the rate- and state-dependent friction law.