Comprehensive Earthquake Cycle Modeling With Multiscale Patches: Unified Simulation Reproducing Observed Laws and Characteristics

Abstract To reproduce characteristics of empirically known seismic activity, such as magnitude‐frequency (M‐F) statistics that follow a power law, the temporal evolution of aftershocks following the Omori formula, and repeating earthquakes with a constant recurrence interval, as well as the rupture initiation process of small and large earthquakes over a long period under a simple model, we conducted quasi‐dynamic numerical simulations of earthquake generation cycles. In the framework of the rate‐ and state‐dependent friction law, we adopted a multiscale circular patch model to represent the spatial heterogeneity of friction in the northern Japan Trench. We divided historical earthquakes with a magnitude greater than 5.6, recorded since 1896, into four groups according to magnitude. We set the characteristic slip distance to be proportional to the patch radius. The M‐F statistics of the simulated earthquakes followed a power law with a smaller magnitude range than that of the characteristic earthquake. Large earthquakes occurred as combined ruptures of nearby patches with different triggering patterns due to foreshocks and slow slip. The rupture initiation points of large, moderate, and small earthquakes were nearly in the same location, suggesting a cascade‐up rupture process. The number of foreshocks and aftershocks of the largest earthquakes statistically followed the modified Omori formula. Small repeating earthquakes occur at isolated patches with recurrence intervals of a few years. The more hierarchical the model, the more complex and varied the seismic cycles. The multiscale circular patch model effectively reproduced these observed characteristics in quasi‐dynamic earthquake cycle simulations.