Change of coastal geometry for long time after a giant tsunami and Strengthening disaster prevention/mitigation function

2021 Fiscal Year Final Research Report

• Project/Area Number: 17H01631
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Natural disaster / Disaster prevention science
• Research Institution: Tohoku University
• Principal Investigator: Imamura Fumihiko 東北大学, 災害科学国際研究所, 教授 (40213243)
• Co-Investigator(Kenkyū-buntansha): サッパシー アナワット 東北大学, 災害科学国際研究所, 准教授 (00648371) ; 後藤 和久 東京大学, 大学院理学系研究科(理学部), 教授 (10376543) ; 小岩 直人 弘前大学, 教育学部, 教授 (70296002) ; 原口 強 大阪市立大学, 大学院理学研究科, 准教授 (70372852)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: 巨大津波 / 地形変化と回復 / 土砂移動 / 防災・減災

Outline of Final Research Achievements

In the 2004 Indian Ocean Tsunami and the 2011 Tohoku-Pacific Ocean Earthquake Tsunami, large-scale topographical changes occurred along the coast due to huge external forces, which had a great impact on subsequent restoration and reconstruction plans. We conducted long-term observations, surveys, and numerical evaluations of topographical changes in Thailand, Sri Lanka, and Tohoku, and predicted future topographical change scenarios. In Thailand, we analyzed the data of photography and photogrammetry by drone and summarized the relationship of the topographical recovery process. In Sri Lanka, we proceeded with particle size analysis and paleoenvironmental analysis, recognized old tsunami deposits, and clarified past environmental changes. On the Tohoku coast, the amount of change in beach topography was estimated from the data before and after the waves, and the relationship between parameter setting and reproducibility could be clarified by sediment movement analysis.

Free Research Field

津波工学

Academic Significance and Societal Importance of the Research Achievements

復旧や復興計画に大きな影響を与えた．この影響は現在も継続しており，さらに予効変動による地盤隆起も加わり，今後数十年を超えるスケールで沿岸部の地形変化が継続するとみられる．したがって，発災後すぐに策定された復興計画は将来的な地形変化や土地利用に応じて柔軟に修正する必要がある，津波後の環境変化の中には，復旧・復興計画が策定される短期間内では評価できない影響が生じる場合がありその実態を評価出来，今後の大災害の後の復旧や復興の段階での留意点などを制することが出来た．