Stick-slip from heterogeneous Coulomb friction.

Stick-slip on preexisting faults has long been associated with velocity-dependent and time-dependent friction. The description, however, has not adequately addressed position-dependent friction, an aspect that is relevant to spatially complex fault zones in nature. Here we show how the interaction between irregular surfaces results in heterogeneous Coulomb friction along the interface. We then conduct dynamic simulations of a spring-slider model and find that heterogeneity in Coulomb friction alone is capable of reproducing a wide range of stick-slip phenomena that may be associated with complex fault slip behaviors, from fault creep and low frequency earthquakes to ordinary earthquakes and slow slip events.