| Project/Area Number |
10480091
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Natural disaster science
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
MINOURA Koji GELOGICAL INSTITUTE, SCHOOL OF SCIENCE, TOHOKU UNIVERSITY, 大学院・理学研究科, 教授 (10133852)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Tomoyuki DISASTER PREVENTION RESEARCH INSTITUTE, KYOTO UNIVERSITY, 防災研究所, 助手 (40261599)
IMMURA Fumihiko DISASTER CONTROL RESERACH CENTER, TOHOKU UNIVERSITY, 工学研究科・附属災害制御研究センター, 教授 (40213243)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥12,300,000 (Direct Cost: ¥12,300,000)
Fiscal Year 2000: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1999: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1998: ¥9,600,000 (Direct Cost: ¥9,600,000)
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| Keywords | Tsunamideposits / Tsunamirunup / Grain-size composition / Carbon age / Mode of sediment transport / Numerical simulation / Coastal topography / Microfossils / 堆積物粒度組成 / 加速器炭素同位体年代 / 堆積の周期性 / 微化石 / 海岸平野 / 数値計算 |
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| Research Abstract |
The fore-arc region of northeast Japan is a terrane of extensive seismic activity and tsunami generation, and the coastal areas facing the Pacific Ocean have been repeatedly attacked by tsunamis. On July 13,869 a tsunami triggered by a large-scale earthquake invaded the coastal zones, causing extensive deposition of well-sorted fine sand over the plains. Sedimentological analysis and hydrodynamic modeling indicate that the sand layer was developed by the first wave of the tsunami, and we conclude that low-lying coastal zones are susceptible to extensive flooding during tsunami runup. Traces of large-scale invasion by older tsunamis are recorded in the coastal sequences at regular chronological intervals, and we indicate that the coastal plains of northeast Japan are in danger of tsunami disasters in the near future.
The Pacific coast of NE Japan is notorious for the repeated invasion of tsunamis. The Sendai plain, however, has not been affected by a large tsunami since the occurrence of
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the Jogan event. Rapid urbanization has advanced to the coastal areas. It must be recognized that understanding of the timing and scale of potential tsunami occurrence is an urgent requirement, if tsunami mitigation efforts on the densely populated coast are to be successful. The elucidation of the cause and effect of regionally extensive invasion of the Jogan tsunami is indispensable not only to prevent a disaster but also to gain an understanding of tectonic processes of the fore arc. In this study, the Jogan tsunami deposits were studied using sedimentological analyses and hydrodynamic models in an attempt to make clear the mechanism of wave penetration more than 4 km beyond the coastline.
More than 100 years have passed since the beginning of scientific observation in NE Japan, and inundation distance of tsunamis exceeding 2 km beyond the shore was never observed during this time interval . It is inferred from the historical documents that seawater inundation by the Jogan tsunami reached 4 km or more inland from the coast. The deep penetration of seawater mean an occurrence of unprecedented large-scale tsunami. Less
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