f 3-D tomographic model study

We evaluated the applicability, of the Simultaneous Iterative Reconstruction Technique (SIRT) in a 3-D environment. Synthetic travel times were generated for various 3-D geometry configurations. We then inverted the synthetic travel times for velocity. This synthetic data also allowed us to evaluate the various survey designs and the artifacts each may produce. In addition, we were able to derive an approximate measure of resolution using point spread functions. We found the SIRT algorithm suitable for resolving reasonable 3-D love-veldcity images. The best images were obtained with Chose geometries producing ray paths that closely surround, and some of which penetrate, the anomalous zone. Ray paths became less useful when originating within the low-velocity zone.