Takigami geothermal system, northeastern Kyushu, Japan

The Takigami geothermal reservoir is bounded by a system of faults and fractures oriented along two main directions, north to south and east to west. The Noine fault has a large vertical displacement and trends north to south, dividing the subsurface characteristics of resistivity, permeability, temperature and reservoir depth. The Takigami geothermal fluid has a near neutral pH and is of the Na-Cl type, with a chloride content ranging from 400 to 600 ppm. The southwestern part of the area has the highest subsurface temperature, up to 250 degrees C. The deep fluid originates from the southwest, and Row is mainly to the north and partly to the east along faults and fractures, decreasing in temperature with increasing lateral flow. (C) 2000 CNR. Published by Elsevier Science Ltd. All rights reserved.