岡山県倉敷市北村地域で発生した土石流災害の特徴と要因 Debris avalanche occurred in Kitamura area, Kurashiki City, Okayama Prefecture
The debris avalanche occurred in Kitamura area, Kurashiki City, Okayama Prefecture caused by the hardrain of Typhoon 12 of September, 2011. Furthermore, 11 small landslides occurred in the study area. In thisarea, the altitude of mountainous are not so high (150m to 250m) and the amount of precipitation whichproducted the debris avalanche was not very serious quantity with 230mm. However the debris avalancheoccurred. One private house collapsed, and the first floor part of the Kitamura Elementary School was burieddue to the debris flow. The purpose of this study is to examine causes of the debris avalanche disasteroccurred in Kitamura area using applied geological technique. The length of the debris avalanche scar isabout 250m, and alluvial fan is formed as a debris slope. The ground is composed of weathered granite andthe bottom of the valley was filled by soils derived from disintegrated granite. There are three smalllandslides as head scarps with steep slopes at approximately 30°-35°. The debris avalanche was inferred tohave started as a shallow soil slip at the head by rainfall. 3 major causes are inferred which originated thedebris avalanche in the study area; steep slope, ground composed of weathered granite, existence of sandysoil which occupied at the bottom of valley.
- Okayama University Earth Science Report
Okayama University Earth Science Report 20(1), 1-6, 2013-12-27