Mechanism of submarine landslide and slide dynamics focusing on water film formation under impermeable layer

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K14823
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Iwai Hiromasa 名古屋工業大学, 工学(系)研究科(研究院), 助教 (80756908)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 海底地すべり / 地すべり津波 / クリープ地すべり / 海底地盤 / 線形安定解析 / 分岐現象 / 模型実験

Outline of Final Research Achievements

The major findings of this study are that (1) submarine landslide motions can be classified into three major patterns, and (2) revealing the relationship between submarine landslide motion and tsunamis characteristics generated by submarine landslides.
The most notable point of (1) is that not only the slide length, but also the time history of landslide velocity is classified into three patterns. In particular, it is found that the case of a large landslide exhibits creep rupture-like behavior, in which the initial velocity is small, but after a steady state of constant velocity, the slip rapidly propagates. For (2), we found that there is a linear relationship between the initial acceleration of a landslide and initial drawdown, and that the gradient is proportional to the thickness of the landslide soil mass.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

本研究成果の学術的意義は，海底地すべりによって津波が励起されるメカニズムの解明に向けての足掛かりになることである。従来の海底地すべり津波の考え方は，海底地形の地質調査から地すべり規模と津波規模を推定するのもあった。これに対して本研究では，海底地すべり運動形態の違いによって発生する津波の特性も異なってくることを明らかにした。言い換えれば，たとえ海底地形の変化が比較的小さくても大きな加速度や速度が観測されれば，大きな津波に繋がる危険性について言及した。本研究成果によって，地震時に沿岸域を襲う津波の規模や到達時間予測の高精度化に繋がることが期待される。