A STUDY ON FLOW AND DEPOSITION AREA OF MUDFLOW TYPE DEBRIS INTENDED FOR LANDSLIDES OF IZUOSHIMA 2013 BY TYPHOON NO.26

Abstract

Mudflows were occurred in Izuoshima Island by typhoon No.26 on 16 October 2013. Izuoshima Island is volcano region formed by the eruption of Mt. Mihara. And the land surface is covered with volcanic ash sediment of 1 meter depth. Because of the volcano ash sediment is fine particle, the layer of ash sediment formed the mud-type debris flow. As a result, the debris flow reached downstream area of Izuoshima with low land gradient. In this study, numerical analysis of the mud-type debris flow in Izuoshima was conducted using the angle of internal friction calculated from laboratory experiment. Results of numerical analysis showed good agreement with the deposition situation in downstream area of Izuoshima.