We inferred a geothermal structure of the Otake-Hatchobaru area based on the three-dimensional seismic velocity structure. A low V
p and V
s region related with the fracture zone at 1 km depth is located at the Otake-Hatchobaru area. Beneath this low V
p and V
s region, a high V
p and high V
s region surrounding a low V
p and high V
s region was found at 3.5 km depth, which is correlated to the granitic basement rocks and their intrusions. The low V
p and high V
s region at 3 km depth is related with the horizontally distributed fracture zone. A high V
p region was revealed at the depths of 5 km except for a part just under the Otake-Hatchobaru area. For the high V
p and low V
s region, we suggest a partial melting zone and a transporting zone of molten fraction. Just under the Otake-Hatchobaru area there is a low V
p and low V
s region at 5 km depth. The low V
p and V
s region continues to 8 km depth. And a low V
p and V
s region was found at 11 km depth to the south of Kuju Volcano. The low V
p and V
s regions are probably related to a recent magmatic body for Kuju Volcano. Therefore, the geothermal structuree at Kuju Volcano imaged from the seismic velocity structure may play an important role in geothermal energy of the Otake-Hatchobaru geothermal area.
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