| Abstract |
Yamagata prefecture, located in the northeast of Japan, has more than 100 hot spring areas and hot spring is used for mainly bathing. The geothermal investigations of these were carried out from late 1960’s by Yamagata prefectural office, then after that the nationwide geothermal survey was carried out from 1980’s. In Yamagata prefecture, the geothermal development promotion surveys were conducted by NEDO in Hijiori, Azuma, Ginzan and Akakura areas. Geothermal resources related to quaternary volcanoes such as Azuma, Zao, and Hijiori areas, are accompanied by high temperature hot springs and hydrothermal alteration zones on the surface at present. A large quantity of thermal waters (above 60 oC ) gushes out in the Zao hot spring. Azuma and Hijiori areas are related with volcanic depression and maximum temperatures of the exploration wells are above 200 oC. Akakura area related with caldera is accompanied by high temperature thermal waters (70 oC). Many non-volcanic hot springs are scattered mainly along the Yonezawa Basin and the Yamagata Basin. Some of the high temperature hot springs such as Akayu, Kaminoyama, Tendo and Higashine are situated on margin of these basins or in volcano-tectonic depressions, which are suitable structures for thermal waters reservoirs. In Yamagata prefecture, there are several promising areas for the small-scale geothermal power development. It is considered to be necessary to continue investigation for geothermal development. |