Integrated analyses of paleotsunami history along the Japan Trench

• Project/Area Number: 17H02971
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geology
• Research Institution: The University of Tokyo (2019-2020); Tohoku University (2017-2018)
• Principal Investigator: Goto Kazuhisa 東京大学, 大学院理学系研究科(理学部), 教授 (10376543)
• Co-Investigator(Kenkyū-buntansha): 横山 祐典 東京大学, 大気海洋研究所, 教授 (10359648) ; 西村 裕一 北海道大学, 理学研究院, 准教授 (20208226) ; 菅原 大助 東北大学, 災害科学国際研究所, 准教授 (50436078) ; 柳澤 英明 東北学院大学, 教養学部, 准教授 (70635995)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥17,810,000 (Direct Cost: ¥13,700,000、Indirect Cost: ¥4,110,000); Fiscal Year 2020: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000); Fiscal Year 2019: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000); Fiscal Year 2018: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000); Fiscal Year 2017: ¥8,450,000 (Direct Cost: ¥6,500,000、Indirect Cost: ¥1,950,000)
• Keywords: 津波堆積物 / 日本海溝 / 地質学 / 数値計算 / 地質調査 / 津波計算

Outline of Final Research Achievements

The objective of this study is to clarify the paleotsunami history along the Pacific coast of East Japan based on the efficient finding of survey sites using Ground Penetrating Radar and numerical modeling. Field survey was performed along the coastal area from Aomori to Chiba Prefectures and we found multiple candidate tsunami deposits at several sites. Based on detail sedimentological, paleontological, and geochemical analyses together with radiocarbon dating, we revealed paleotsunami history and size of each event. Among them, we investigated the 3000 years paleotsunami history at Choshi City of Chiba Prefecture and revealed that there were three large tsunami events at this site. The timing of these events were relatively close to those occurred at central Japan Trench.

Academic Significance and Societal Importance of the Research Achievements

東日本大震災をきっかけに，地質学的古津波研究の重要性が社会的に認知されるようになった．本研究では，特に日本海溝南部での古津波履歴について詳細に明らかにし，日本海溝中部での巨大地震・津波の発生と時期を前後して南部でも発生する可能性があることを指摘した．これは，日本海溝周辺の一部で巨大地震が発生すると周辺域の歪バランスが変化し，時期を隔てて巨大地震を引き起こす可能性を検証する必要があることを示唆している．同時に，2011年東北地方太平洋沖地震津波を受けて日本海溝南部（外房沖）での近い将来の巨大地震・津波発生可能性を十分に評価する必要がある．

Research Products

• [Journal Article] Ten years after the 2011 Tohoku-oki earthquake and tsunami: Geological and environmental effects and implications for disaster policy changes (2021)
  • Author(s): Goto, K., Ishizawa, T., Ebina, Y., Imamura, F., Sato, S., Udo, K.
  • Journal Title: Earth-Science Reviews Volume: 212 Pages: 103417-103417
  • DOI: 10.1016/j.earscirev.2020.103417
  • Peer Reviewed / Open Access
• [Journal Article] Three thousand year paleo-tsunami history of the southern part of the Japan Trench (2021)
  • Author(s): Higaki, H., Goto, K., Yanagisawa, H., Sugawara, D., Ishizawa, T.
  • Journal Title: Progress in Earth and Planetary Science Volume: 8 Issue: 1 Pages: 28-28
  • DOI: 10.1186/s40645-021-00415-w
  • Peer Reviewed / Open Access
• [Journal Article] Dating tsunami deposits: Present knowledge and challenges (2020)
  • Author(s): Ishizawa Takashi、Goto Kazuhisa、Yokoyama Yusuke、Goff James
  • Journal Title: Earth-Science Reviews Volume: 200 Pages: 102971-102971
  • DOI: 10.1016/j.earscirev.2019.102971
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A scheme proposal for an effective selection of survey sites in paleotsunami research, Hachinohe case, Aomori Prefecture, Japan (2019)
  • Author(s): Velasco, E., Goto, K., Sugawara, D., Nishimura, Y.
  • Journal Title: Proceedings of the 2019 CWMD Conference Volume: - Pages: 189-198
  • Peer Reviewed
• [Journal Article] Non-destructive analyses to determine appropriate stratigraphic level for dating of tsunami deposits (2019)
  • Author(s): Ishizawa Takashi、Goto Kazuhisa、Yokoyama Yusuke、Miyairi Yosuke
  • Journal Title: Marine Geology Volume: 412 Pages: 19-26
  • DOI: 10.1016/j.margeo.2019.02.009
  • Peer Reviewed / Open Access
• [Presentation] 石巻平野における歴史津波堆積物の年代制約 (2019)
  • Author(s): 手塚寛，後藤和久，石澤尭史，菅原大助，横山祐典，宮入陽介
  • Organizer: 日本地球惑星科学連合大会
• [Presentation] 地質・歴史記録に基づく日本海溝南部の波源モデルの再検討 (2019)
  • Author(s): 檜垣北斗，後藤和久，柳澤英明，菅原大助
  • Organizer: 2019年度津波堆積物研究会
• [Presentation] A scheme proposal for an effective selection of survey sites in paleotsunami research, Hachinohe case, Aomori Prefecture, Japan (2019)
  • Author(s): Velasco, E., Goto, K., Sugawara, D., Nishimura, Y.
  • Organizer: 2019 CWMD Conference
  • Int'l Joint Research
• [Presentation] 元素・安定同位体比分析による歴史津波堆積物の検出 (2018)
  • Author(s): 小形祐介，後藤和久，篠崎鉄哉，池原実，Chague Catherine，川又隆央
  • Organizer: 日本地球惑星科学連合2018年大会
• [Presentation] 千葉県銚子市の過去3000年間の古津波履歴 (2018)
  • Author(s): 檜垣北斗，後藤和久，柳澤英明，菅原大助，石澤尭史
  • Organizer: 日本地球惑星科学連合2018年大会
• [Presentation] The 2011 Tohoku-oki earthquake and tsunami -6 years on (2017)
  • Author(s): Goto, K.
  • Organizer: IGCP 630 meeting in Japan
  • Int'l Joint Research
• [Presentation] GPR survey for paleotsunami research, Workshop on GPR measurement of active faults and tsunami sediments (2017)
  • Author(s): Goto, K., Takeda, H., Goff, J., Matsumoto, H., Sugawara, D.
  • Organizer: French-Japanese Week on Disaster Risk Reduction (宇宙・航行エレクトロニクス研究会（SANE))
  • Int'l Joint Research