Noise Removal and 3D Interpretation of Magnetotelluric Data in the Pohang Low-Enthalpy Geothermal Area, Korea

Abstract

We conducted magnetotelluric (MT) measurements in the Pohang area, southeastern Korea, in 2002 and 2003, as one of the initial surveys for the development of low-enthalpy geothermal resources in the area. Korea is one of the most difficult countries in the world from the point of MT data acquisition. It is because artificial electromagnetic noises from power lines and other various man-made sources are very strong over almost whole country. We therefore applied a very far remote reference by setting a remote site in southwestern Japan in order to overcome the noises. Although very strong artificial noises were observed at a wide frequency band from 0.1 Hz to 100 Hz, the remote reference processing successfully removed most of these noises. The resultant data have sufficient quality for further interpretation. We then carried out 3D inversion of the MT data and compared with geological and drilling data in the area. In this paper, we present the remote referenced results and the 3D resistivity models of the Pohang geothermal area.