Joint Inversion of MT and DC Resistivity Data at Hatchobaru Area

Abstract

In November and December 1984, a magnetotelluric (MT) survey was conducted on and near the Hatchobaru Geothermal Power Station property of Kyushu Electric Power Company (KEPCO) in North Central, Kyushu, Japan. The objectives of the survey were 1) to extend and add to the result of a previous MT survey carried out in the fall of 1982, 2) to better define a low resistivity zone associated with present reservoir at Hatchobaru, 3) to located stable remote reference station in order to obtain data with less noise bias than the previous survey and 4) to determine if there are another areas of low resistivity in a larger aerial section. The MT and DC resistivity data were simultaneously interpreted by the ridge regression investgation. Electrical resistivity sections derived form the joint inversion would be useful in determining more accurately the depth to the geothermal reservoirs and were compared with drilling logs of exploratory wells which were drilled according to the results of this survey. It is confirmed that the southeast area show promising potential for an extension of the second geothermal power plant.