Takigami geothermal system, northeastern Kyushu, Japan

The Takigami geothermal reservoir is bounded by a system of faults and frac tures 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, tem perature and reservoir depth. The Takigami geothermal fluid has a near neut ral pH and is of the Na-Cl type, with a chloride content ranging from 400 t o 600 ppm. The southwestern part of the area has the highest subsurface tem perature, 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 fr actures, decreasing in temperature with increasing lateral flow. (C) 2000 C NR. Published by Elsevier Science Ltd. All rights reserved.