2004 Volume 57 Issue 4 Pages 48-55_1
Several slope failures and debris flows occurred on September 29, 2004 in Miyagawa village, Mie prefecture. The geological background around Miyagawa village consists of metamorphic rocks of Sambagawa belt and sedimentary rocks of Chichibu belt, and the bedrocks near the surface were strongly weathered. The heavy rainfalls caused by the typhoon Mean (T 0421) triggered these sediment disasters. Cumulative rainfalls at several rain gauges in Miyagawa village were about 600-700mm, and hourly rainfalls were about 100-125mm/h around 8: 00 to 10: 00 a.m. Cumulative rainfall in Miyama town located at southern side of Miyagawa village exceeded 1, 000mm and the maximum hourly rainfall reached to 150mm/h (8: 00-9: 00 a.m.). Therefore, many slope failures and debris flows occurred from 8: 00 to 12: 00 a.m. As a result of these heavy rainfalls, six deaths and one missing person were recorded and 44 houses or sheds were completely broken or lost.