阿蘇カルデラ西部地域の地震活動

概要

論文の詳細を見る
Several earthquake swarms have been occurred at the western region of the Aso Caldera. Some of them have consisted of over a hundred events between magnitude 1 to 4. The seismic observation has been carried out for the earthquakes originating at the region during long period since 1964, in order to determine the long term behavior of seismicity. The obtained data have provided a detailed feature of the seismic activity along the western caldera rim. The upper crust of the western caldera region is divided into the northern and southern areas at the Tateno-valley, which is the collapsed part of the caldera wall. At the northern area, the seismicity is very active and the most of foci have concentrated in the shallow part above 7km depth. The b-value for the events at the northern area is comparatively larger than the value at the southern area. On the contrary, at the southern area the seismicity shows calm and the foci have not been present in the shallow part above 5km depth and have been extensively scattered below 10km depth. These results seem to be closely related to that the tectonic line runs across the Tateno-valley from east to west. Most of events at the northern area have been showing as swarms with the high degree of clustering in time and space. At the periods of seismic swarm activities, the bvalues have trended to be decrease. These earthquake swarms appear to be accompanied by the volcanic activities of the Aso Volcano. The focal mechanisms have been also analyzed for the events at the northern area. The composite fault plane solution for events at the area has not been able to be determined because of the complicated distribution of first motions. It seems to correspond to that some small normal faults are existing in a parallel arrangement from north to south at the northern area.
1981-12-28

阿蘇カルデラ西部地域の地震活動

スポンサーリンク

概要

著者

関連論文

スポンサーリンク