1. Upslope Failure Mechanisms and Criteria in Submarine Landslides: Shear Band Propagation, Slab Failure and Retrogression.
- Author
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Zhang, Wangcheng, Klein, Boaz, Randolph, Mark F., and Puzrin, Alexander M.
- Subjects
STOREGGA slides ,FINITE element method ,LANDSLIDES ,GEOTECHNICAL engineering ,ENGINEERING geology - Abstract
The volume of a submarine landslide is likely to be amplified by shear band propagation along a basal surface or spreading failure extension in the sliding layer. Although the mechanism of translational submarine landslides has been understood using the interpretation of shear band propagation, assessment of the limits of failure extension, either through shear band propagation or retrogressive spreading, remains a challenge due to the diversity of post failure mechanisms. The paper aims to explore all post failure possibilities and quantify failure initiation and extension accordingly, focusing on the upslope conditions. The different failure mechanisms are explored with the aid of the large deformation finite element modeling. Original criteria for scarp position, shear band length at slab failure, retrogression conditions and ultimate spreading limits are proposed, following the process zone approach considering force equilibrium of the sliding mass. Simplified analytical predictions are shown to agree well with the numerical observations. The findings and criteria presented in the study are expected to help assess the ultimate scale of upslope failure in submarine landslides, which is important in determining geohazard zonation of submarine landslides. Plain Language Summary: Submarine landslides are often huge compared to onshore counterparts, but why and how huge? Answering these questions will increase our understanding of submarine landslide evolution and help to assess risks of submarine landslide recurrence. For example, the Storegga Slide offshore Norway, which occurred ∼8,200 years ago, covered an area as large as UK and triggered tsunami waves seriously impacting nearby islands. A large submarine landslide might be initiated from localized failure within an embedded weak layer, followed by failure propagation along the weak layer and extensive slab failure in the overlying sliding layer. These two post‐failure phenomena may greatly increase the scale of submarine landslides. Here we simulate submarine landslides in different conditions and explore all possible upslope post‐failure mechanisms, using a large deformation numerical modeling method. Based on the observed mechanisms, we develop a new model and original criteria to predict the scarp position and failure extension limit of submarine landslides. Altogether, findings here are expected to help assess the ultimate scale of submarine landslides, which is important in determining geohazard zonation of submarine landslides. Key Points: We explore and quantify all upslope failure possibilities of submarine landslides through numerical modeling and theoretical analysesWe establish a framework for assessing failure initiation, covering different failure mechanismsWe propose simple predictions for scarp position and retrogression limit, which allows rapid assessment of scale of submarine landslides [ABSTRACT FROM AUTHOR]
- Published
- 2021
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