3D Acoustic-Elastic Simulations for Tsunami-Genesis

Fundamental mechanisms of how earthquakes induce tsunamis, such as the influence of complex geometry, time-dependent rupture, and the role of ocean compressibility, are still unclear. Such simulations often use a two-step model, where the earthquake and tsunami are modeled in separate simulations with one-way coupling using the earthquake-induced seafloor displacements. We follow an alternative approach in which we simulate both the earthquake and tsunami in a fully coupled manner. The Earth is modeled as an elastic material, the ocean as an acoustic one. We have extended the open-source seismic-wave propagation and earthquake dynamics solver SeisSol (seissol.org) with elastic-acoustic coupling. SeisSol uses the ADER discontinuous Galerkin method on unstructured tetrahedral meshes, which together with local time-stepping allows for tsunami-earthquake scenarios with realistic geometries. SeisSol scales with good parallel efficiency from standard production scenarios to full-machine runs. To implement the elastic-acoustic coupling, we use the exact Riemann solver (Wilcox et al., 2010). We use a linearized gravitational free surface boundary condition (Lotto and Dunham, 2015) to incorporate tsunami generation and propagation. We verified the numerics, including the boundary conditions, with analytical solutions (Abrahams et al., AGU 2019). Additionally, we will show scenarios that can be used to investigate the effects of earthquake rupture dynamics on tsunami genesis.     «

Fundamental mechanisms of how earthquakes induce tsunamis, such as the influence of complex geometry, time-dependent rupture, and the role of ocean compressibility, are still unclear. Such simulations often use a two-step model, where the earthquake and tsunami are modeled in separate simulations with one-way coupling using the earthquake-induced seafloor displacements. We follow an alternative approach in which we simulate both the earthquake and tsunami in a fully coupled manner. The Earth is...     »