A community faulted-crust model using PYRAMID on cluster platforms

Development has boosted the GeoFEST system for simulating the faulted crust from a local desktop research application to a community model deployed on advanced cluster platforms, including an Apple G5, Intel P4, SGI Altix 3000, and HP Itaniam 2 clusters. GeoFEST uses unstructured tetrahedral meshes to follow details of stress evolution, fault slip, and plastic/elastic processes in quake-prone inhomogeneous regions, like Los Angeles. This makes it ideal for interpreting GPS and radar measurements of deformation. To remake GeoFEST as a high-performance community code, essential new features are Web accessibility, scalable performance on popular clusters, and parallel adaptive mesh refinement (PAMR). While GeoFEST source is available for free download, a Web portal environment is also supported. Users cap work entirely within a Web browser from problem definition to results animation, using tools like a database of faults, meshing, GeoFEST, and visualization. For scalable deployment, GeoFEST now relies on the PYRAMID library. The direct solver was rewritten as an iterative method, using PYRAMID'S support for partitioning. Analysis determined that scaling is most sensitive to solver communication required at the domain boundaries. Direct pairwise exchange proved successful (linear), while a binary tree method involving all domains was not. On current Intel clusters with Myrinet the application has insignificant communication overhead for problems down to /spl sim/1000s of elements per processor. Over one million elements run well on 64 processors. Initial tests using PYRAMID for the PAMR (essential for regional simulations) and a strain-energy metric produce quality meshes.