A Model of Earthquake-Generation Cycle with Scale-Dependent Frictional Property - Preliminary Results and Research Plan for a Project of Evaluation for Coming Tokai, Tonankai, and Nankai Earthquakes

To estimate rupture timing and location for coming Nankai trough earthquakes, we must know the mechanism of variation in earthquake size and recurrence time. Recurrence time varies fairly widely, and shows time-predictable behavior based on historical data. We propose a conceptual model for reproducing recurrence-timing variation related to earthquake size. The model includes smaller patches in a larger patch where all patches are velocity-weakening. We assume that characteristic slip distance L under the rate- and state-dependent friction law depends on patch size. We test simple two-scale heterogeneity and reproduce time-predictable behavior. Results show that slip patterns among earthquake-generation cycles vary significantly. Within a seismogenic zone, after-slip occurs during interseismic periods of giant earthquakes rupturing the entire seismogenic zone.