2003 Fiscal Year Final Research Report Summary
Periodicity of large-scale landslide revealed by the landslide-lake sediments and ancient documents
| Project/Area Number |
13640458
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geology
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| Research Institution | Gifu University |
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Principal Investigator |
KAWAKAMI Shin-ichi Gifu University, Faculty of Education, Department of Geology, Associate Professor, 教育学部, 助教授 (80183036)
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| Co-Investigator(Kenkyū-buntansha) |
KOIDO Yoshimitsu Gifu University, Faculty of Education, Department of Geology, Professor, 教育学部, 教授 (60101424)
徐 勝 核燃料サイクル開発機構, 東濃地科学センター, 研究員
KOJIMA Satoru Gifu University, Faculty of Engineering, Department of Civil Engineering, Professor, 工学部, 教授 (20170243)
XU Sheng Tono Geoscience Center, Japan Nuclear Cycle Development Institute, Researcher
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| Project Period (FY) |
2001 – 2003
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| Keywords | landslide / large-scale slope faulure / landslide-lake / periodicity / ancient document / accretionary complex / Mino terrane |
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| Research Abstract |
Prediction of large-scale landslides with more than one million cubic meters of landslide debris is important in central Japan with steep-slope topography, because they cause heavy damages on infrastrucutes. Three largest landslides (Nan'notani, Neoshiratani and Tokuyamashiratani landslides) are know to occur during last one hundred years in the Mino terrane. Two of them occurred at the sites with specific geologic structures : the resistant limestones against weathering and erosion are thrust over the weak melanges. These geologic structures formed at the time of accretion, and are useful to predict the future slides in the Mino terrane. Similar geologic structures are present in the Funafuseyama, Ibukiyama, Ryozensan and Fujiwaradake areas. Very large-scale landslides in the western slope of Ibukiyama dammed-up the Anegawa River flowing on the foot of the mountain, and formed landslide lakes. We measured the 14C ages of the lake sediments and revealed the ages of the lakes to be 34,000 and 5,200 years before present. The Sekigahara pass south of Ibukiyama has been the most important traffic route connecting eastern and western Japan, and many ancient documents described landslide events at Ibukiyama. We analyzed these documents and found that the landslide events occured at about 890, 1500, 1700 and 1909 (Anegawa earthquake) AD. These events made no landslide lakes, and the events 34,000 and 5,200 years before present making the landslide lakes were quite large in scale
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