Laterally propagating slow slip events in a rate and state friction model with a velocity-weakening to velocity-strengthening transition

We investigate the behavior of simulated slow slip events using a rate and state friction model that is steady state velocity weakening at low slip speeds but velocity strengthening at high slip speeds. Our simulations are on a one-dimensional (line) fault, but we modify the elastic interactions to mimic the elongate geometry frequently observed in slow slip events. Simulations exhibit a number of small events as well as periodic large events. The large events propagate approximately steadily “along strike,” and stress and slip rate decay gradually behind the propagating front. Their recurrence intervals can be determined by considering what is essentially an energy balance requirement for long-distance propagation. It is possible to choose the model parameters such that the simulated events have the stress drops, slip velocities, and propagation rates observed in Cascadia.