Multi-event simulations of slow slip events for a Cascadia-like subduction zone

We employ the earthquake simulator, RSQSim, which incorporates rate-and state-dependent friction, to investigate characteristics of slow slip events (SSEs) along a Cascadia-like mega-thrust. The simulations consist of 100,000 SSEs with equivalent moment magnitudes M(w)4.0-7.0. The largest simulated SSEs (M(w)6.4-7.0) have interevent times of similar to 19 months, durations of 10-40 days, mean slips of 2.2-4.1 cm, and along-strike propagation speeds of 7-20 km/day, which are comparable to observations from Cascadia. The simulations show quiescence after M-w > 6.4 SSEs, followed by a progressive increase in both the magnitude and frequency of SSEs prior to the next large event. Small SSEs, below similar to M(w)5.6, develop in an incoherent manner and have irregular geometries, while larger SSEs show highly coherent growth of the slip region and spontaneous, but transient, event-to-event segmentation. The change in event characteristics at similar to M(w)5.6 corresponds to a break in the scaling of seismic moment with slip, fault area, and duration. Citation: Colella, H. V., J. H. Dieterich, and K. B. Richards-Dinger (2011), Multi-event simulations of slow slip events for a Cascadia-like subduction zone, Geophys. Res. Lett., 38, L16312, doi:10.1029/2011GL048817.