As the coastal industry expands its operations into deepwater fields, concerns over the safety of marine engineering facilities under extreme geological hazards have become increasingly pronounced. Submarine landslides, as common marine geological hazards, pose potential threats to nearshore structures (such as oil and gas platforms and wind turbine foundations), submerged cables and mooring systems. The prediction of potential risks associated with submarine landslides and the safety assessment of seabed structures have become paramount. In previous studies, several equations have been proposed to estimate the impact force caused by submarine landslides. These equations typically relate the impact force to the dynamic characteristics of the slide, particularly the frontal velocity and thickness of the slide, and empirical resistance coefficients of the subsea structures. However, accurately predicting the spatiotemporal-variated submarine landslides and determining the empirical resistance coefficients pose significant challenges. Consequently, there is currently no widely accepted method for evaluating the impact risk of submarine landslides.

In this paper, a two-phase Smoothed Particle Hydrodynamics (SPH) model is utilized to simulate and discuss the impact process caused by submarine landslides. In this model, the water-sediment and inter-sediment actions are fully considered. By analyzing the momentum evolution of the landslide before and after the impact process, an assessment based on the momentum framework is proposed to evaluate the safety of seabed facilities under the threat of submarine landslides.