Reconnaissance of Thermal Spring Sites in the Aleutian Arc, Atka Island to Becherof Lake

Abstract

Twenty of more than 30 thermal springs in the Aleutian arc, extending from Atka Island to Becherof Lake, were investigated July and August 1980. Subsurface reservoir temperatures in excess of 150°C are estimated for 10 of the thermal spring sites investigated. These site all occur in or near regions of recent volcanism. Five thermal spring sites have reservoir temperatures in the range of 90°-150°C and occur either near recent volcanoes or near lineation's that suggest fracture or fault control. There sites identified as having reservoir temperatures <90°C, occur at or near the coast and appear to be related to local fractures or dikes. Thermal activity at three other sites had diminished substantially or no longer existed. Three locations are highly promising for developing and using geothermal energy; Akutan Island, northern Unalaska Island, and northeast Atka Island. All three areas have high temperature geothermal resources that are located near existing population centers with well protected, deep water harbors.