Using Dynamic Rupture Simulations to Assess Megathrust Earthquake Behaviors in the Cascadia Subduction Zone

The Cascadia subduction zone dominates the earthquake hazard in the United States Pacific Northwest. It is oft-cited that the probability of a magnitude ~9 (M9) event occurring in the coming decades is 10 - 14% (Peterson et al., 2002). Outstanding questions for its next megathrust earthquake include where it will initiate, what conditions are dynamically favorable for an M9 event to develop, and how much slip may occur offshore. We present a suite of dynamic rupture simulations to address these questions by combining recurrence intervals (T) estimated by paleoseismic data with geodetic coupling models to constrain dynamic stress-drop on the megathrust. Uncertainty in offshore megathrust coupling is explored with different geodetic slip-rate deficit models and variable T. Our simulations solve for elastodynamic rupture propagation using the open-source software package SeisSol.