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

Abstract

[1] 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 Mw4.0–7.0. The largest simulated SSEs (Mw6.4–7.0) have inter-event times of ∼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 Mw > 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 ∼Mw5.6, 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 ∼Mw5.6 corresponds to a break in the scaling of seismic moment with slip, fault area, and duration.