A Simulation of Seismic Wave Propagation at High Resolution in the Inner Core of the Earth on 2166 Processors of MareNostrum

We use 2166 processors of the MareNostrum (IBM PowerPC 970) supercomputer to model seismic wave propagation in the inner core of the Earth following an earthquake. Simulations are performed based upon the spectral-element method, a high-degree finite-element technique with an exactly diagonal mass matrix. We use a mesh with 21 billion grid points (and therefore approximately 21 billion degrees of freedom because a scalar unknown is used in most of the mesh). A total of 2.5 terabytes of memory is needed. Our implementation is purely based upon MPI. We optimize it using the ParaVer analysis tool in order to significantly improve load balancing and therefore overall performance. Cache misses are reduced based upon renumbering of the mesh points.