Evaluating Triggering Mechanisms of Submarine Landslides: Insights from Centrifuge Testing and Numerical Analysis

This paper presents an investigation into specific triggering mechanisms of submarine landslides, integrating centrifuge test data and numerical simulations to examine the role of pore water pressure (PWP) and ground motion intensity measures (IMs) in submarine slope failure mechanisms. A series of pulse-like ground motions (PLGMs) were selected for numerical simulations after validating the model with results from a centrifuge test. Data spanning from 1974 to 2024 highlighted static liquefaction and seismic activity as key triggers for submarine landslides. However, less than 3% of geotechnical centrifuge tests conducted over this period specifically addressed submarine landslides. The collected data revealed a clear relationship between slope failure angles and the PWP ratio (ru), showing that even a small increase in PWP (ru = 0.1) can destabilize relatively gentle slopes. Moreover, comparisons between analytical methods and empirical data demonstrated that accounting for dynamic PWP improves the accuracy of predictions for seismic submarine landslide behaviour by analytical methods. The numerical analysis further indicated that energy-based IMs, correlate more strongly with seismic submarine sliding displacement than amplitude-based IMs. Moreover, the deviatoric strains significantly contributed on the submarine slope displacement. These findings underscore the critical importance of accurate PWP estimating and advanced estimation techniques for assessing submarine slope stability, particularly in seismic environments.