reached at a depth of 100 m was 122◦C . In 2004,the area Y2 was again drilled to a depth of 56 m to extract the hot fluid. Its temperature at that depth is around 94◦C . The hot water is currently used for spas anddrying agricultural products. In the initial assessments of the MaeChan region concluded that the shallow fluids are not hot enough to generate electricity and drilling to depths of 1 km in the granite was not cost-effective. To assess the sizeof the reservoir without costly drilling, a magnetotelluric (MT)survey was conducted. The MT surveys are widely used in the pastdecades in geothermal exploration to reveal hydrothermal systemsbeneath the surface and to help define the drilling locations for theproduction wells (Heise et al., 2008; Newman et al., 2008). This is because of its major advantage as it is the only method that candirectly sense a geothermal reservoir from its electrical resistivityfrom the surface down to depths of several kilometers