Speaker
Description
Thanks to seismic interferometry, even tiny velocity changes in the subsurface following sizeable earthquakes can be detected with increasing spatial resolution. It remains a substantial challenge to forecast such velocity (or better elastic module) changes in a quantitative way. However, it is clear that such nonlinear behavior may considerably affect the ground shaking and thus needs to be accounted for if reliable forecasting of strong ground motion is desired. Here, we report on the addition of a specific nonlinear (damage) model to the wave and rupture simulation code seissol that is based on the discontinuous Galerkin method using tetrahedral meshes to discretize Earth’s structure and faults. The parameters of the nonlinear model are constrained by laboratory measurements. The numerical solution is applied to a realistic structure and rupture model of the 2015 Mw 7.83 Gorkha Earthquake in Nepal. The results show co-seismic velocity reductions up to 50% in a wide area around the fault with values affected by the existence of a sedimentary basin, varying with basin depth as well as fault slip distributions. The results suggest that such physics-based damage models should be considered not only for accurate estimations of strong ground shaking for earthquake scenarios but also when using observed motions to understand rupture processes.
