Earthquake ground motion modeling on parallel computers

We describe the design and discuss the performance of a parallel elastic wave propagation simulator that is being used to model and study earthquake-induced ground motion in large sedimentary basins. The components of the system include mesh generators, a mesh partitioner, a parceler, and a parallel code generator, as well as parallel numerical methods for applying seismic forces, incorporating absorbing boundaries, and solving the discretized wave propagation problem. We discuss performance on the Cray T3D for unstructured mesh wave propagation problems of up to 14 million tetrahedra. By paying careful attention to each step of the process, we obtain excellent performance despite the highly irregular structure of the coefficient matrices of the problem. The mesh generator, partitioner, parceler, and code generator have been incorporated into an integrated toolset/compiler. This system, called Archimedes, automates the solution of unstructured mesh PDE problems on parallel computers, and is being used for other unstructured mesh applications beyond ground motion modeling.