Two catastrophic debris avalanches triggered by rainstorms in Japan and Philippines
Two cases of landslides: the September 29, 2004, Miyagawa slide in Japan and the February 17, 2006, Leyte slide in Philippines both triggered by heavy rainstorms were studied and documented herein. This study clarified the following points: (1) The main process of mass movement is not debris flowbut debris avalanche in both cases. (2) Heavy rainfall as a causal factor for landslide is much greater in the case of the Miyagawa slide than in the Leyte slide. The major causal factor for the Leyte slide is the accumulation of ground creep. (3) Numerous hummocks were found in the deposits at the Leyte slide, while numerous large rock blocks were found in the deposits at the Miyagawa slide. The former resulted from the fragmentation of soft rock and the latter from fragmentation of hard rock during avalanching. (4) The Miyagawa slide closed the main stream of a river forming a landslide dam, which breached immediately due to a strong hydraulic force of high water without full impoundment in the reservoir, while the Leyte slide did not close the main stream because of a broad flood plain of the river. Although the two landslides showthese differences, they display high mobility that must come from a sufficient water condition which enables a full development of the liquefied layer of debris in the bottom boundary of avalanches.
rock slide debris avalanche debris flow rainstorm Miyagawa Southern Leyte
H. Suwa S. Nakaya
Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan Graduate School of Science, Kyoto University, Kyoto, Japan
国际会议
成都
英文
341-351
2007-05-17（万方平台首次上网日期，不代表论文的发表时间）