Permalink : http://hdl.handle.net/2115/38148

JaLCDOI : 10.14943/gbhu.72.117

We conducted a total field magnetic survey in the 2000 eruption area of Mt Usu. A distinct negative magnetic anomaly was found in the geothermal field in the NW part of the survey area. Meanwhile, no clear magnetic anomaly was found around N-B crater, where active fumaroles were seen. Regarding the negative anomaly in the geothermal field, we performed a 3-D inversion of demagnetized prism model. As a result it has been suggested that the magnetic anomaly is due to the demagnetization at a small depth less than 70 m from the ground surface.