Abstract
A numerical simulation of seismic cycles on a plate boundary is performed using a rate- and state-dependent friction law. The spatial distribution of frictional constitutive parameters is determined so that the simulated seismic cycles may mimic the occurrence of large earthquakes in the northern Sanriku area along the Japan trench. Two patches with velocityweakening frictional properties are assumed to represent two large asperities that were ruptured in the 1968 Tokachi-oki earthquake (Mw=8.2). By choosing appropriate friction parameters, I can simulate the recurrence of large earthquakes that break both the velocityweakening patches at a recurrence interval of 90 years. During each interseismic period of the simulated large earthquakes, one of the velocity-weakening patches is broken, resulting in the occurrence of a smaller earthquake. This may correspond to the occurrence of the 1994 Sanriku-oki earthquake of Mw=7.7. The coseismic slip amounts in the simulation are similar to those estimated for the 1968 Tokachi-oki and the 1994 Sanriku-oki earthquakes, and postseismic sliding is reproduced in the velocity-strengthening region. These simulation results for seismic cycles at the northern Sanriku subduction zone suggest that the frictional constitutive parameters on the plate boundary can be estimated to some extent. The model with realistic friction parameters is expected to be useful for forecasting the sliding process on the plate boundary.
