2D Inversion of VES and MT Data in a Geothermal Area

Abstract

In the Hatchobaru geothermal area, various geophysical methods have been conducted for geothermal explorations by West JEC and Kyushu Electric Power Company Inc., (KEPCO). Especially, Schlumberger VES and Magneto- Telluric (MT) surveys have been used for locating promising drill sites as the most effective geophysical tools in the fractured-type geothermal resources. However, there are often inherent difficulties in determining 3D resistivity structures from a layered earth model alone in a difficult area. In order to solve this problem, Vertical Electric Sounding data with Schlumberger electrode arrangement and MT data were simultaneously interpreted by the least squares curve-fitting method based on 2D model. In the present paper, 3D resistivity structure including present production zones have been derived from 2D inversion results of VES and MT data in the Hatchobaru geothermal field in Japan.