Session III:
Physically-based simulation of earthquike generation and the earthquake cycle

2nd ACES (APEC Cooperation for Earthquake Simulation) Workshop in Japan

Elastodynamic analysis of earthquake sequences on slowly loaded faults with rate and state friction
Nadia Lapusta, James Rice


Lapusta et al., 2000 have developed an efficient and rigorous numerical procedure for elastodynamic analysis of earthquake sequences on slowly loaded faults. This is done for a general class of rate and state friction laws with positive direct velocity effect. We use the procedure to study the response of a 2-D strike-slip fault model with depth-variable properties. We find the following (as partially reported by Lapusta et al., 2000: Small events appear in increasing numbers for decreasing values of the characteristic slip distance of the friction law. The nucleation phase of small and large events is very similar. For a large event that is preceded by a small event (and hence heterogeneous stress distribution), moment acceleration in the beginning of dynamic propagation exhibits "slow-downs" and subsequent "speed-ups", consistently with some observations. Insufficient time and space discretization qualitatively changes the results. Incorporating slow tectonic loading is essential for uncovering the true model response.

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