Elastic-Acoustic Coupling for 3D Tsunamigenic Earthquake Simulations with ADER-DG on Unstructured Tetrahedral Meshes

To enable physics-based 3D simulations of tsunami genesis due to earthquakes, we extend the open-source seismic wave propagation solver SeisSol (seissol.org) to scenarios which couple seismic waves in an elastic Earth to acoustic and gravity waves in an overlying water layer. SeisSol exploits unstructured tetrahedral meshes to account for complex geometries with high resolution topography, bathymetry and 3D subsurface structure. It supports frictional fault failure and uses a high-order ADER discontinuous Galerkin (ADER-DG) scheme with local time-stepping to achieve high accuracy and efficiency. The highly tuned parallel implementation enables large-scale simulations. We present the integration of elastic-acoustic coupling in the numerical scheme and its implementation in SeisSol. This allows us to explore multi-physics scenarios that couple the earthquake dynamics, seismic wave propagation through the potentially complex subsurface of subduction zones and their traversal through an acoustic medium with self-consistent tsunami generation. To accurately treat elastic-acoustic interfaces, we solve the Riemann problem exactly (Wilcox et al., 2010). In addition, we investigate a linearized free surface boundary condition (Lotto and Dunham, 2015) acting on the acoustic layer that incorporates gravitational effects and permits simulation of tsunami generation and propagation. All of these components interact with each other and form a dynamic and fully coupled simulation. We verify the resulting model with a benchmark scenario for physics-based earthquake-tsunami coupling (Madden et al., 2019). This scenario includes an earthquake emanating from an embedded fault and wave propagation through both acoustic and elastic media. Here, we will focus on exploring the effects of the boundary conditions. Furthermore, we will discuss the usage of code generation for the efficient realization of our new features and the design of a user-friendly configuration interface for boundary conditions.     «

To enable physics-based 3D simulations of tsunami genesis due to earthquakes, we extend the open-source seismic wave propagation solver SeisSol (seissol.org) to scenarios which couple seismic waves in an elastic Earth to acoustic and gravity waves in an overlying water layer. SeisSol exploits unstructured tetrahedral meshes to account for complex geometries with high resolution topography, bathymetry and 3D subsurface structure. It supports frictional fault failure and uses a high-order ADER dis...     »