Earthquake Simulations at Petascale - Optimizing High Order ADER-DG in SeisSol

Michael Bader, Technische Universität München

This talk will give a comprehensive overview on the end-to-end optimization of the earthquake simulation code SeisSol for current petascale supercomputers. SeisSol performs multiphysics simulations of the dynamic rupture process coupled to seismic wave propagation. Its key strengths are its ability to treat geometrically complex tectonic faults (due to the use of unstructured adaptive tetrahedral meshes) and its high accuracy and arithmetic intensity stemming from the Arbitrary high order DERivative Discontinuous Galerkin (ADER-DG) discretization. We will discuss implications of the high-order DG discretization (in space and time) on time- and energy-to-solution and we will outline algorithmic and implementational improvements required to achieve high computational efficiency, including the recent implementation of local time stepping. A special focus will also be on improvements in SeisSol's I/O strategy (scalable mesh input, output of results, checkpointing, e.g.). Finally, we will report on experiences and key finding from scalability tests of SeisSol on various petascale machines, such as Tianhe-2, Stampede and SuperMUC.