Wedge Plasticity and Coupled Simulations of Dynamic Rupture and Tsunami in the Cascadia Subduction Zone

Date: 4/24/2019

Time: 06:00 PM

Room: Grand Ballroom

In an elastic dislocation model, whether or not a subduction plate boundary fault breaks the trench has a significant effect on the seafloor deformation and resulting tsunami. However, this boundary condition at the trench plays an insignificant role when plastic deformation in the overriding wedge is considered. Several seismic profiles along the Cascadia subduction zone indicate that the subduction megathrust does not reach the trench. Coupled dynamic rupture and tsunami simulations for a buried fault in Cascadia incorporating realistic fault geometry, bathymetry, and velocity structure have been carried out in Lotto et al. (2018) assuming elastic dislocation. Here we extend that model by incorporating wedge plasticity, which we will show can be more efficient than slip on a buried fault in generating seafloor uplift and tsunami. In the Cascadia subduction zone, which contains large amounts of sediments in the overriding wedge, wedge plasticity may be a very important factor in tsunami generation.

Presenting Author: Andrew L. Wilson

Authors