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Published November 2003 | public
Book Section - Chapter

A 14.6 billion degrees of freedom, 5 teraflops, 2.5 terabyte earthquake simulation on the Earth Simulator


We use 1944 processors of the Earth Simulator to model seismic wave propagation resulting from large earthquakes. Simulations are conducted based upon the spectral-element method, a high-degree finite-element technique with an exactly diagonal mass matrix. We use a very large mesh with 5.5 billion grid points (14.6 billion degrees of freedom). We include the full complexity of the Earth, i.e., a three-dimensional wave-speed and density structure, a 3-D crustal model, ellipticity as well as topography and bathymetry. A total of 2.5 terabytes of memory is needed. Our implementation is purely based upon MPI, with loop vectorization on each processor. We obtain an excellent vectorization ratio of 99.3%, and we reach a performance of 5 teraflops (30% of the peak performance) on 38% of the machine. The very high resolution of the mesh allows us to perform fully three-dimensional calculations at seismic periods as low as 5 seconds.

Additional Information

© 2003 ACM. All the simulations were performed at the Earth Simulator Center of JAMSTEC by S. T. Broadband seismogram data used in this study were obtained from the IRIS Data Management Center (www.iris.washington.edu). Three of the authors (D. K., C. J. and J. T.) were funded in part by the U.S. National Science Foundation. S. T. was funded by a Grant-in-Aid for Scientific Research (KAKENHI 13640426) from the Japan Society for the Promotion of Science. We thank four anonymous reviewers for comments that improved the manuscript. We also thank Brian Savage from Caltech for providing software that plots seismograms on maps.

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