Subsurface geothermal activity has a thermal expression that can be observed at the surface. Such spatial temperature gradients are within the radiometric resolution that is characteristic of a wide range of satellites that carry thermal sensors. For this effort, CIRES (part of the University of Colorado) used a hierarchical approach in which we examined data from Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) onboard Landsat platforms and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra satellite to digitally model warm surface exposures. Geological characteristics such as faulting and other available datasets for known thermally active areas in Colorado were used in conjunction with the satellite thermal imagery to rank potential areas of geothermal activity.

This report outlines the approach and methodology of the utilization of thermal satellite imagery to find areas of warm ground that might indicate heat flow from a buried geothermal system. The satellite platforms, modeling equations and corrections to the data are discussed. Some specific findings from the survey are shown, together with conclusions.