This report presents three types of evidence documenting that the combination of P-wave and S-wave seismic data provides geologic insights that cannot be provided by conventional P-wave data alone.

Focusing on the highly developed Edwards aquifer, which supplies water for a large area of south-central Texas, this report presents a three-dimensional model of the porosity distribution in the aquifer, which quantifies the spatial distribution of water resources and provides information that can be used in ground-water flow and transport models. The study provides a detailed assessment of the amount of water in the Edwards aquifer as of 1996 on the basis of a large data set and a reproducible methodology.