Geological and Geophysical Perspective of Supercritical Geothermal Energy in Subduction Zone, Northeast Japan

Geological and geophysical characteristics of supercritical geothermal reservoirs in the Tohoku District, NE Japan were investigated in order to evaluate potential of future geothermal energy. Geological information in the Tohoku District (caldera, hot spring hydrothermal alteration, mine, and granitoid) and geophysical data (gravity, MT and seismicity) were accumulated into GIS database. We can evaluate present volcanism and related events, geothermal structure, depth of heat source, fracture distribution, and existence of fluid by using the GIS database. We identify the following geological features in terms of geothermal resources: “Deep fluid input”, “Magma input”, “Geothermal gradient”, and “High temperature hot spring”, and we can classify the geothermal energy and potentials as follows: “Promising”, “Probable”, “Possible”, and “Potential”.