## Exploration Activity: Numerical Modeling At Coso Geothermal Area (2000)

Determine areas with fault patterns for geothermal development using Poisson's ratio and porosity

High-resolution, three-dimensional, compressional and shear wave velocity models, derived from microearthquake travel times, are used to map the distribution of Poisson's ratio and porosity at Coso Geothermal Area. Spatial resolution of the three-dimensional Poisson's ratio and porosity distributions is estimated to be 0.5 km horizontally and 0.8 km vertically. Model uncertainties, + or -1% in the interior and + or -2.3% around the edge of the model, are estimated by a jackknife method. Perturbations of r = V

_{p}/V

_{s} ratio and Psi = V

_{p}dot V

_{s} product were used to derive distributions of Poisson's ratio, sigma , and porosity, which are then used to constrain and delineate possible zones of intense heat, fracture accumulation and fluid saturation. Poisson's ratio at Coso ranges from 0.15 to 0.35 with an average of 0.224, lower than the crustal average of 0.25.

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