Numerical simulations of complex earthquake cycles are conducted using a model with two patches (asperities) on a fault, where friction obeys a rate‐and‐state‐dependent law. The patches are represented by regions of steady‐state velocity‐weakening friction and are in contact with each other or are separated by a region of steady‐state velocity‐strengthening friction. Simulated earthquake cycles are examined by changing the characteristic slip distance of friction in one patch, while that in the other patch is maintained at a constant. As the characteristic slip distance in a patch increases, the slip at the patch tends to be aseismic and rupture tends to be delayed, as compared to rupture at the other patch, or arrested due to an increase in fracture energy. As a result, the slip pattern changes in a complicated manner with the change of the parameter. A complex multiperiodic or aperiodic slip pattern occurs in the simulation, and this pattern tends to occur near the boundaries between regions of different slip behavior characteristics, such as the boundary between seismic and aseismic slip in the patch with a larger characteristic slip distance. Iteration maps of the recurrence intervals of simulated earthquakes for an aperiodic sequence are sometimes expressed by simple curves, suggesting that the simulated earthquake cycles exhibit deterministic chaos. In the two‐patch models of the present study, an aperiodic slip pattern is observed for narrower parameter ranges than in a model of a two‐degree‐of‐freedom spring‐block system, which is usually regarded as a simplified model of a fault with two patches.
Online Material: Simulated histories of moment release rate and recurrence interval of simulated slip events in the two patches and seismic coupling coefficients.