Terrestrial Heat-flow Measurements in an Underground River Located in the Eastern Snake River Plain, Idaho

Abstract

A heat flow survey of the eastern Snake River Plain, Idaho, was initiated to determine the regional tectonic implications and to assess the geothermal potential. High surface heat flow values, 3 HFU or greater, are observed on the margins of the eastern SRP. Regional considerations suggest that the heat flow should be high throughout the whole eastern SRP; however, in the center of the eastern SRP, the observed surface heat flow pattern show negative values in the east (Idaho Falls area) with a gradual increase to about 1.5 HFU at the west (Hagerman-Twin Falls area). The observed heat flow values are controlled by groundwater flow in the Snake Plain Aquifer. Flow rates in the aquifer are as high as several meters per day. A model of the aquifer is presented to explain the pattern of low surface heat flow while high heat flow is present under the aquifer. Data from intermediate depth wells (1km) and deep wells (2-3 km) being drilled will soon be available to indicate the nature of heat flow present under the aquifer.