The Hohi Geothermal Area, Kyushu, Japan

Abstract

Geophysical data from surface measurements and downhole pressure temperature data i n exploritory well for a 112 km regin in northern Kyushu centered around Mount Waita are examined. The study area includes the geothermal fields supplying steam f o r the Hatchobaru and Ohtake power stations, but a1 so extends a considerable distance to the northwest. Evidence from d r i l l i n g logs, magnetotelluric surveys, l o s t- circulation horizons, downhole temperature surveys, and thermal and chemical properties of surface hot-spring discharge suggests the presence of a large geothermal reservoir north of the towns of Takenoyu and Hagenoyu.