Construction of an erotic and depositional process model by a huge tsunami in the seismic beach ridge plain

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K03767
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Nanayama Futoshi 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 上級主任研究員 (20357685)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 地震性浜堤列平野 / 巨大津波 / 侵食堆積過程モデル / 超巨大地震（17世紀型） / 千島海溝 / 海溝型地震 / バリアー砂堆 / 地震隆起

Outline of Final Research Achievements

In the coastal area of eastern Hokkaido, there are many barrier sand piles that are still active, which is rare in Japan. It is understood that they were uplifted by the 17th century megathrust earthquake and have continued to subside until now, but the evidence is not clear. As a clue to the solution of this problem, we tried to identify the barrier sand deposits that were separated by the 17th century earthquake in the Bettoga marsh, Horokayanto lagoon on the Tokachi Coast, and Kinashibetsu marsh. As a result, it was clarified that the amount of uplift varies greatly depending on the area and is 0.4 to 1.7 m or more, especially that the Shiranuka Hills area is uplifted.

Free Research Field

地質学

Academic Significance and Societal Importance of the Research Achievements

道東沿岸地域の別当賀湿原，十勝海岸のホロカヤントー，キナシベツ湿原において，17世紀地震によって離水したバリアー砂堆を特定することを試みた．その結果，隆起量は地域によって大きく異なり0.4から1.7 m以上であること，特に白糠丘陵地域が隆起していること，等が明確となった．この事実から，千島海溝において超巨大地震（17世紀型）が発生する際に，まず地震に連動して前弧スリーバーの西進し，これに伴い白糠丘陵や日高山脈が隆起する地震テクトニクスが示唆された．