Three-dimensional traveltime tomography at a shallow groundwater contamination site
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I performed traveltime tomography on a 3-D seismic refraction dateset collected at Hill Air Force Base, Utah in 2000. The survey covers a 95m by 36m area over a contaminated aquifer that is bounded below by a clay aquiclude, in which a paleochannel acts as a trap for the contaminants. Presented are results using an iterative, nonlinear, traveltime tomographic approach applied to 187,877 traveltimes. The resulting velocity model shows that the near-surface velocity increases by roughly a factor of 5 in the upper 15m, from about 300m/s to 1500m/s. Cross-sections through the model show a north-south trending low-velocity feature interpreted to be the channel structure. Checkerboard tests applied to the velocity model establishes a 7.5m lateral resolution throughout most of the depth range of interest. While the long wavelength features of the model reveal the paleo-channel, the velocity model is likely a broad and smooth characterization of the true velocity structure.
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Azaria, Aron. "Three-dimensional traveltime tomography at a shallow groundwater contamination site." (2003) Master’s Thesis, Rice University. https://hdl.handle.net/1911/17572.