後生掛地熱地域で発生する地熱微動

抄録

Measurements of seismic noise have been made in the Goshogake geothermal area, northern Japan, in order to study the nature of the waves originated from geothermal activities. Two kinds of the geothermal seismic noise were detected from the amplitude and power spectral analyses: One is that contains high frequency component from 20 to 45Hz with large amplitude. The origin of the noise is surface geothermal activities. Another is that contains rather low frequency component near 10Hz with moderate amplitude. The noise may originate from boiling of hot water below the surface. Generally, the amplitudes and predominant frequencies obtained in the western part of this area in 1982 decreased as compared with those obtained in 1981. This fact is coinsident with the westward migration of geothermal activities in this area. It is also useful to observe the geothermal seismic noise for monitoring geothermal activities.