High performance earthquake simulations in viscoelastic media using SeisSol

Carsten Uphoff, Michael Bader, Sebastian Rettenberger, & Alice-Agnes Gabriel

Published September 7, 2016, SCEC Contribution #6601, 2016 SCEC Annual Meeting Poster #341

The software package SeisSol simulates seismic wave propagation and dynamic rupture. Being based on unstructured tetrahedral meshes, the software may be used in highly complex scenarios with respect to fault geometry and heterogeneous materials. The underlying discontinuous Galerkin method with ADER time-stepping features high-order accuracy in space and time and allows for an efficient implementation on modern supercomputers. The software was shown to achieve petaflop performance as well as high parallel efficiency on Xeon and Xeon Phi based supercomputers in large scale dynamic rupture scenarios. Furthermore, SeisSol's dynamic rupture implementation has been verified using several SCEC test cases, including rate-and-state friction laws, heterogeneous initial conditions, and fault branching.

In order to achieve petascale, SeisSol's code base was heavily changed to incorporate shared memory parallelization, asynchronous communication, parallel I/O, and hardware aware computational kernels. Until recently, the latter were only available for elastic rheological models. We present our recent efforts to extend the high performance kernels to support viscoelastic attenuation. To this end, we have optimized and extended our code generator for the innermost kernels. The generator now automatically detects irrelevant matrix entries in matrix chain products, determines zero-paddings for hardware conformity, and enables block decompositions for structured sparse matrices. We believe that these changes will simplify high performance implementations of future extensions such as anisotropy or poroelasticity.

The high performance implementation of attenuation was validated on a plane wave problem, showing high-order convergence, and a layer over halfspace problem (LOH.3). The performance results indicate a similar efficiency as in the elastic case. Furthermore, we simulated a dynamic rupture scenario based on the 1994 Northridge earthquake using a power-law Q model. Here, we achieve about 30% of peak performance on 14336 cores.

Key Words
attenuation, dynamic rupture, ADER-DG

Citation
Uphoff, C., Bader, M., Rettenberger, S., & Gabriel, A. (2016, 09). High performance earthquake simulations in viscoelastic media using SeisSol. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Computational Science (CS)