The Crustal Thickness of the Great Basin: Using Seismic Refraction to Assess Regional Geothermal Potential

Abstract

When assessing the geothermal potential of the Great Basin, crustal thickness provides valuable regional-scale information: if the crust is thin, Earth’s mantle is closer to the surface, heat flow can be higher, and the potential for geothermal energy may be greater. In addition, crustal thickness when combined with temperature gradient, gravity, fault location, and strain rate data sets, can allow us to better understand the factors that control the occurrence of geothermal activity. In order to assess the crustal thickness of the Great Basin in poorly constrained areas, we have completed three long-range seismic refraction transects. Our Northern Walker Lane (NWL) refraction experiment, completed in 2002, confirms the presence of a thin crust ranging from 19-23 km-thick in a 100 km-wide region near Battle Mountain, Nevada (Louie et al., 2004) with a southern extent defined by our 2004 Idaho-Nevada- California (INC) transect. Both tomography model sections show an unexpectedly deep crustal root (>50 km) beneath the northern and central Sierra Nevada. Our third experiment, the 2005 Northern-Nevada-Utah transect (NNUT) will provide crustal thickness data in an area with geothermal potential and where no refraction data currently exist. We have also complied a contoured crustal thickness map for the Great Basin from current results of the INC and NWL experiments, as well as other previous work in the region.