Tsunamis and splay fault dynamics

Abstract

The geometry of a fault system can have significant effects on tsunami generation, but most tsunami models to date have not investigated the dynamic processes that determine which path rupture will take in a complex fault system. To gain insight into this problem, we use the 3D finite element method to model the dynamics of a plate boundary/splay fault system. We use the resulting ground deformation as a time‐dependent boundary condition for a 2D shallow‐water hydrodynamic tsunami calculation. We find that if the stress distribution is homogeneous, rupture remains on the plate boundary thrust. When a barrier is introduced along the strike of the plate boundary thrust, rupture propagates to the splay faults, and produces a significantly larger tsunami than in the homogeneous case. The results have implications for the dynamics of megathrust earthquakes, and also suggest that dynamic earthquake modeling may be a useful tool in tsunami research.