Comprehensive study on slope disaster in Izu Oshima Island caused by Typhoon 26 in 2013

2014 Fiscal Year Final Research Report

• Project/Area Number: 25900002
• Research Category: Grant-in-Aid for Special Purposes
• Allocation Type: Single-year Grants
• Research Institution: The University of Tokyo
• Principal Investigator: TOWHATA Ikuo 東京大学, 工学(系)研究科(研究院), 教授 (20155500)
• Co-Investigator(Kenkyū-buntansha): HIROOKA Toshihiko 九州大学, 理学研究院, 教授 (90253393) ; KAWANO Tetsuya 九州大学, 理学研究院, 助教 (30291511) ; NAKADA Setsuya 東京大学, 地震研究所, 教授 (60128056) ; MIYABUCHI Yasuo 熊本大学, 教育学部, 准教授 (30353874) ; MAENO Fukashi 東京大学, 地震研究所, 助教 (20444078) ; MATSUSHI Yuki 京都大学, 防災研究所, 准教授 (90596438) ; TERAJIMA Tomomi 京都大学, 防災研究所, 准教授 (50353777) ; HATTANJI Tsuyoshi 筑波大学, 生命環境系, 講師 (00418625) ; UCHIMURA Taro 東京大学, 工学系研究科, 准教授 (60292885) ; GOTO Satoshi 山梨大学, 医学工学総合研究部, 准教授 (80303395) ; WAKAI Akihiko 群馬大学, 理工学研究院, 教授 (90292622) ; OU Kouki 京都大学, 防災研究所, 助教 (50372553) ; KOKUSHO Takaji 中央大学, 理工学部, 教授 (80286955) ; TAKEBAYASHI Hiroshi 京都大学, 防災研究所, 准教授 (70325249) ; IMAIZUMI Fumito 静岡大学, 農学部, 准教授 (80378918) ; SHIMIZU Yoshihiko 群馬大学, 理工学研究院, 教授 (70178995) ; TAMURA Keiko 新潟大学, 危機管理本部, 教授 (20397524) ; USHIYAMA Motoyuki 静岡大学, 防災総合センター, 教授 (80324705)
• Co-Investigator(Renkei-kenkyūsha): DOI Issei 京都大学, 防災研究所, 助教 (00572976) ; YAMADA Masumi 京都大学, 防災研究所, 助教 (60456829)
• Project Period (FY): 2013 – 2014
• Keywords: 豪雨 / 斜面災害 / 火山 / 防災 / 早期警報

Outline of Final Research Achievements

A comprehensive study was made after the 2013 slope disaster in Izu Oshima induced by an extremely heavy rainfall event. The research team was composed of people from such disciplines as geology， hydrology， meteorology， geotechnical engineering and disaster mitigation science. Emphases were placed on the causative mechanism of the disaster on the basis of field studies， revealing the limitation of current disaster mitigation principles and future improvement for better safety. The damaged volcanic slope was made of interbedding of volcanic ash， lava and other materials and their different hydraulic conductivities affected the slope instability during heavy rain. The current early warning based on rainfall criterion does not consider the topography and geological/soil-mechanic issues and needs to be supplemented by more local monitoring of slope behavior. Further care is needed on evacuation practice because mid-night evacuation during heavy rain may claim additional victims.

Free Research Field

地盤工学