Simulation of seismic cycles of buried intersecting reverse faults

To understand how reverse fault systems interact, I perform a numerical simulation of seismic cycles. The model fault system in a two‐dimensional uniform elastic half‐space consists of a shallowly dipping listric main reverse fault and a subfault with a higher dip angle. A fixed slip rate is imposed on deeper parts of the main fault, and frictional stress on the remaining parts of the main fault and on the subfault obeys a rate‐ and state‐dependent friction law. The main results of the numerical simulation are as follows: (1) Because of fault interactions, there exists moderate scatter in recurrence intervals of large earthquakes on the main fault and the subfault. (2) The cumulative slip amounts on deeper parts of the main fault, on shallower parts of the main fault, and on the subfault are different from one another. Their values are such that the stress concentration at the fault intersection is a minimum. (3) A large earthquake on the main fault increases shear stress and decreases normal stress on the subfault, causing slip on deeper parts of the subfault. A subfault earthquake sometimes induces slip on the main fault. Result 3 is consistent with some seismic observations that two conjugate fault planes were active during an earthquake sequence. Results 1 and 2 may be important for long‐term evaluation of seismic potential.