Self-Potential Survey Results Makushin Volcano Geothermal Area, Unalaska Island, Alaska

Abstract

A self potential survey covering about 78 line km was conducted in the Makushin Volcano area of Unalaska Island, in the Aleutian Island chain. Two major anomalies were seen; one of -600 mV maximum negative amplitude covering about 15 km2, and the second of -500 mV maximum negative amplitude covering about 7 km2. The anomalies do not appear to be caused by artificial sources, variations in soil properties, conductive mineral deposits, or topographic effects. A preliminary analysis of geothermal source mechanism indicated that the depth to the source lies between about 0.30 and 0.50 km for both anomalies, which corresponds to the depth to high temperature gradient measured beneath one of the anomalies. These self potential source regions may correspond to areas where anomalously high flows of heat and/or fluid interest geological boundaries.