Geothermal Seismic Noise Measurements in the Takenoyu Geothermal Area, Central Kyushu, Japan

Abstract

Measurements of seismic noise have been made in the Takenoyu geothermal area, central Kyushu, Japan in order to study the nature of waves originated from geothermal activities. Spatial variation of the average amplitude shows high levels of seismic noise extending over the hot ground. We consider such seismic noise is caused by geothermal activities. The geothermal seismic noise mainly consists of body wave and the depth of the origin is estimated to be about 10 to 30 m below the surface. Considering the distribution of the underground temperature of this area, the origin of the geothermal seismic noise may be boiling of hot water in the upper part of the geothermal reservoir.