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[SSS17-01] Numerical simulation of dynamic earthquake triggering based on rate- and state-dependent friction law
Keywords: dynamic earthquake triggering
We conducted numerical simulations of earthquake triggering assuming a circular asperity obeying RSF law revised by Nagata et al. (2012). In a situation where earthquakes repeatedly occur, we apply dynamic stress disturbance of sinusoidal variation at a certain time. The dynamic stress change causes increase of slip velocity following the RSF law, and resultant slip weakens the frictional strength. This leads to dynamic earthquake triggering depending on the amplitude of the disturbance. When the stress disturbance is sufficiently large, earthquake occurs during the period of stress oscillating. This might correspond to dynamic triggered earthquakes during passage of seismic waves. When static stress is also increased, smaller dynamic disturbance can trigger earthquakes with a shorter delay. Even if static stress change is negative, a certain amplitude of dynamic stress change can trigger earthquakes.
Figure 1 shows relation between the time to instability and the increase of logarithm of the slip velocity at the center of the asperity. Red, blue, and green circles denote triggering due to static stress change, dynamic stress change, and both stress change, respectively.