阿蘇カルデラ周辺の地震活動と発震機構

Abstract

In the central Kyushu, the active seismic region is restricted in the western part. The easternside area of this region is the Aso and Kuju Volcanoes.Particularly, near the Aso Caldera, several earthquake swarms have been occurred. Thefault plane solutions of earthquakes in this area were obtained by the seismic network of AVL(Aso Volcanological Laboratory, Kyoto Univ.). The solutions indicate that the faults are as-sumed the northeast-southwest normal type or strike-slip type faults. All of tension axes arehorizontal in the north-south direction. These evidences (the stress-field is characterized byremarkable north-south extension) are confirmed in the seismic active region of the central Kyushu.