Joint Inversion of Geophysical Data as a Geothermal Exploration Tool: Applications to Yellowstone Park and the Imperial Valley

Abstract

We have developed a three dimensional earth modeling procedure for delineating the subsurface structure in geothermal areas. The procedure is the simultaneous generalized inversion of multiple geophysical data sets. A significant advantage of this approach is that maximum use is made of the information content and inherent resolving power of the available data from a geothermal region, thus providing an integrated interpretation of the earth's near surface structure. The inversion technique has been applied to data sets from the Imperial Valley and Yellowstone Park. For each region, teleseismic travel time residuals and gravity data were jointly inverted to obtain a three dimensional model of the P velocity an density of the crust and upper mantle. The Imperial Valley model is characterized by substantial crustal thinning beneath each of the KGRA's. The Yellowstone model contains two zone s of low density/low velocity crustal material beneath the resurgent domes within the Yellowstone caldera. The zones merge at depth an may be associated with chambers of partially molten rock.