[S-CG58] Brittle-Ductile Transition and Supercritical Geofluids for Crustal Energy in Island Arc

[SCG58-09] Preliminary report on geothermal structure revealed by geological and MT surveys around Akayumatasawa river in Sanzugawa caldera, NE Japan

*Keishi Nunohara¹, Kuo Hsuan Tseng², Hiroki Okano¹, Yasuo Ogawa², Noriyoshi Tsuchiya¹ (1.Graduate school of Environmental Studies Tohoku University , 2.Graduate school of Science , Tokyo Institute of Technology)

Keywords:geothermal structure, MT, geothermal fluid

Inner part of Sanzugawa caldera, NE Japan, is one of the promising geothermal areas that had been found by many geological and geophysical surveys after 1970’s. In this area, one geothermal power plant (Uenotai geothermal power plant) is currently in operation, and additional one (Wasabizawa geothermal power plant) is being constructed now.

There are a number of high-temperature hot springs along Akayumatasawa river that flows through the center of Sanzugawa caldera. This study reports the resistivity and geological structures based on MT surveys and field surveys around Akayumatasawa. In addition to these structures, the gravity structure, distribution of hot springs, and hypocenter clusters under Akayumatasawa indicate existence of geothermal fluid that is ascending from deep subsurface.