日本地球惑星科学連合2014年大会

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インターナショナルセッション(口頭発表)

セッション記号 H (地球人間圏科学) » H-DS 防災地球科学

[H-DS05_29AM2] Landslides and related phenomena

2014年4月29日(火) 11:00 〜 12:40 415 (4F)

コンビーナ:*千木良 雅弘(京都大学防災研究所)、王 功輝(京都大学防災研究所)、今泉 文寿(静岡大学農学部)、座長:王 功輝(京都大学防災研究所)

12:25 〜 12:40

[HDS05-12] 地震波形記録から見た2013年10月16日の伊豆大島における斜面崩壊の特徴

*土井 一生1釜井 俊孝1王 功輝1森田 裕一2 (1.京大学防災研、2.東大地震研)

キーワード:斜面崩壊, 地震波形, 土砂流動

On Oct. 16, 2013, large-scale slope failure took place due to extreme rainfall in Izu-Oshima Island in Japan. The precipitation reached over 90 mm per hour from 1:00 to 5:00 before and during the period when the failures took place. Through geological surveys by us and Natural Disaster Research Council, piping holes were observed on the collapsed slopes, which suggested that the ground water spouted due to high water pressure. It is important to grasp the detailed behaviors of water and sediment movement in order to reduce the slope disaster in the volcanic regions.Signals of failures and their related sediment movements were recorded many times by several seismometers installed around by Oshima Volcano Observatory of ERI, Univ. of Tokyo. The seismic signals were observed almost at the same time at several stations. Four major signals were detected from 2:00-3:00, while at least a few tens were observed from 3:00-5:00. These signals had unclear initial phases and long (several minutes) durations. The amplitudes increased almost at the same time at the beginning among the stations, while the times when they attained the maximum values were earlier at the stations located in the upper side of the slope. These facts indicate that the vibrations were firstly generated in the upper side of the slope, then moving toward the downside.Acknowledgments: We used meteorological data recorded by JMA.