CFD-DEM simulation of submarine landslide triggered by seismic loading in methane hydrate rich zone

Submarine landslide due to seismic loading in methane hydrate-rich zone was simulated in this study using coupled computational fluid dynamics and discrete element method. Dynamic features and Magnus force were incorporated in the coupling scheme to improve the simulation fidelity in dynamic problem. A sinusoidal type seismic loading was applied to a steep submarine slope, which was characterized by a strong inter-layer of methane hydrate-bearing sediments. The simulation results show that a flow-type sliding occurs and the sliding ends with a gentle slope of accumulated debris material. The fluid flows in an eddy pattern near the sliding mass. The presence of methane hydrate can increase the strength and decrease the damping of the sediment. When MH saturation is low (25 and 30%), the combined seismic loading and particle-fluid interaction damage the MH-rich layer, which allows settlement behind the slope crest and upheaval in front of the slope toe. The two ground deformation patterns (settlement and upheaval) are not observed when MH saturation is high (40 and 50%) because the sediment strength is great enough to resist seismic damage. The lower damping in higher MH saturation sediment allows more energy to be transferred from ground base to potential sliding mass and consequently the sliding initiates earlier. Implications of the simulation results in the assessment of earthquake-induced submarine hazards are discussed.