Precision Earthquake Relocation and the Estimation of Empirical Seismic Travel-time Surfaces
Professor Gary Pavlis from the Indiana University Department of Geological Sciences has developed a new analysis tool for precision earthquake location. Location of earthquakes in the Earth is complicated by the fact that the Earth is a natural system with variations in seismic wave velocities that vary at all spatial scales.
The approach Pavlis has developed uses a novel method that associates all events in an earthquake catalog to one or more grid points in space. The arrival time data for events linked to each of these grid points is then inverted for revised event locations and a set of travel time path corrections to each grid point. The method is exact and allows other model information to be folded into the solution to provide a precision, absolute location estimate for each earthquake in the data set. This is a high performance computing problem because it requires millions of modest size matrix inversions computations (several per node point with data associations). The algorithm is, however, highly suited to parallel computing. We implemented a foreman-worker model with a the foreman passing data for an individual grid to a single processor for computations. Workers pass their output to a database writer process that provides indexed storage to the voluminous output.
For more information, see: http://www.indiana.edu/~geosci/
