焼岳火山地域における地動データの利用による土石流等発生位置の決定

Abstract

We demonstrated to determine the location and origin time of the debris flow using the ground motion data recorded with short period seismometers around the Yake-dake volcano and Kamikochi area, central Nagano prefecture, Japan. Seismic waves radiated from the debris flow are assumed as the surface wave and their location and origin time are determined so that RMS of the difference between theoretical and observed amplitude of the seismic signal are minimized by grid search method. We applied this procedure to the ground motion data of the debris flow that occurred near Ubuya-sawa valley, Kamikochi area in June 23, 2011 and could determine the location and time which well coincide with other filed investigations. We suppose this method can be one of the powerful tools to determine the location and the origin time of the mass movement phenomenon such as not only debris flow but also pyroclastic flow around the volcanoes.