Stratigraphic and historical study on landslides on tephra-rich slopes
| Project/Area Number |
15K01251
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Natural disaster / Disaster prevention science
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| Research Institution | Kumamoto University |
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Principal Investigator |
Miyabuchi Yasuo 熊本大学, くまもと水循環・減災研究教育センター, 教授 (30353874)
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| Project Period (FY) |
2015-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Keywords | 斜面崩壊 / 土石流 / テフラ層序 / 歴史学的調査 / 災害発生履歴 / 火山 |
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| Outline of Final Research Achievements |
Unconsolidated superficial tephra deposits that cover the volcanic edifices have great potential for generating serious sediment disasters. The generation mechanism and frequency of landslides on tephra-rich slopes were examined based on tephrostratigraphic and historical studies. Most of the landslides were shallow soil slips (<2 m thick) in unconsolidated tephra deposits overlying lava flows and pyroclastic rocks in the cases of Aso caldera in July 2012 and Izu Oshima volcano in October 2013. Physical differences of tephra deposits above and below the rupture surfaces including grain size, hardness and permeability promote the retention of rainwater in the upper layer, leading finally to failure and mobilization of the saturated mass. Tephra chronology and radiocarbon dating on paleosols along the succession suggest that rainfall-induced landslides and the associated lahars on the eastern wall of Aso caldera occurred at an interval of 400-1800 years.
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| Academic Significance and Societal Importance of the Research Achievements |
阿蘇火山周辺域における1953年以前の土砂災害発生履歴について検討した研究は現在のところ見当たらない．この地域では近年，テフラ層序に関する研究が進展し，鍵層の年代が明らかになっており，災害発生頻度を評価するための好条件がそろっている．また，熊本・阿蘇地域に保管されている古文書の調査など歴史学的手法を組み合わせて，土砂災害発生履歴について検討したことが本研究の特色である．研究対象地域は今後も噴火災害のほか，豪雨による土砂災害発生ポテンシャルが極めて高い．本研究で得られた結果は，将来の防災計画を策定するうえで重要であり，他の火山地域での土砂災害の抑止・軽減にも貢献するものである．
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Report
(6 results)
Research Products
(38 results)
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[Journal Article] The September 14, 2015 phreatomagmatic eruption of Nakadake first crater, Aso Volcano, Japan: Eruption sequence inferred from ballistic, pyroclastic density current and fallout deposits2018
Author(s)
3.Miyabuchi, Y., Iizuka, Y., Hara, C., Yokoo, A., Ohkura, T.
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Journal Title
Journal of Volcanology and Geothermal Research
Volume: 351
Pages: 41-56
DOI
Related Report
Peer Reviewed / Int'l Joint Research
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[Presentation] The September 14, 2015 explosive eruption at Nakadake first crater, Aso Volcano, SW Japan2019
Author(s)
Miyabuchi, Y., Iizuka, Y., Hara, C., Yokoo, A., Ohkura, T.
Organizer
IAVCEI 5th Volcano Geology Workshop
Related Report
Int'l Joint Research
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