How Small Slip Surfaces Evolve Into Large Submarine Landslides—Insight From 3D Numerical Modeling

Abstract

Submarine landslides are a major marine geohazard affecting resilience of offshore infrastructure and coastal urban centers. Attention has previously been paid to quantifying post‐failure dynamics of catastrophic submarine debris flows and their consequences. However, pre‐failure initiation and growth of a small slip surface evolving into a large submarine landslide are still less understood. This study aims to explore the physical failure mechanism of submarine landslides initiated from small slip surfaces and to quantify key features of failure evolution. They are achieved by modeling the entire three‐dimensional (3D) landslide evolution, integrating the initiation and growth of slip surface, failure of slab above the slip surface, post‐failure mass movement and re‐deposition of transported sediments, using a novel numerical method. The characteristics of the slip surface growth within a favored layer and the patterns of the slab failure in the overlying layer have been thoroughly discussed. The transition from the pre‐failure slip surface growth to the diverse post‐failure mass movement are first observed and discussed with the 3D geometry effects, revealing the complex cascading mass movement mechanisms. The criterion for unstable growth of a planar slip surface and critical condition for slab failure are proposed. The findings from the study facilitate scientific understanding of the evolution of historic events and help safeguarding offshore developments against submarine landslide recurrence.

A Depth-Averaged Material Point Method for Shallow Landslides: Applications to Snow Slab Avalanche Release

“…The latter author reports a ratio between cross-slope and down/up slope dimensions of the release area to be around 2.1 for unconfined conditions. The shape of our release area also differs from that of Zhang & Puzrin (2022) with a mismatch very likely due to a different slab constitutive model (von Mises versus CCC).…”

“…Gaume & Reuter (2017) and Reuter & Schweizer (2018) later proposed novel methods to describe snow instability by combining limit equilibrium and finite element simulations. More recently Zhang & Puzrin (2022) proposed a depth-averaged finite difference method for the initiation and propagation of submarine landslides. Yet, so far, approaches combining a mechanical release model, variable material properties and complex topography are still scarce.…”

A GIS framework for prediction of basin‐wide post‐failure geometry of confined subaqueous landslides

“…The depth-integrated method is used to model terrestrial and submarine landslides in cases where the thickness of the sliding body is significantly smaller than its length. [37][38][39][40][41][42] The small thickness to length ratio of such slides allows the stresses and strains of the sliding body to be averaged over its thickness. As a result, the numerical model can be represented by a set of finite bar elements connected via mutual nodes (Figure 3).…”

“…This assumption may have its limitation when considering a margin polygon (e.g., see polygon 1 in Figure 14). In this work, we use the outermost lateral extent of such polygons and construct lines normal to the contour lines to create the associated quasi-stable polygons, 18,19,42 however, have studied the effect of out-of-plane geometry on the critical shear stress ratio for planar and conical slopes. Their studies showed that the shear surface may grow in the transverse direction due to downslope movement of the sediments and that the growth extent is related to the aspect ratio and area size of the pre-softened zone (or failure initiation zones in this case).…”

“…22 Over the years, a considerable amount of work has been devoted to the understanding of these mechanisms and the estimation of their potential dimensions. Among the methods used were analytical energy-based criteria 20,[23][24][25][26] and limit equilibrium [27][28][29] and various numerical methods such as large deformation finite element analysis, 28,[30][31][32] material point method, 33,34 smooth particle hydrodynamics, 35 particle finite element method, 36 depth-integrated methods [37][38][39][40][41][42] and more.…”