Mapping submarine landslides susceptibility in continental slopes with rich gas hydrates

Abstract

Gas production from oceanic hydrates could trigger large submarine landslides. To screen out the sites susceptible to perturbation, this paper proposes a physically-based model for assessing the susceptibility of submarine landslides in continental slopes where gas hydrates are widespread. The model does not require an inventory of historical submarine landslides that are often incomplete or unavailable. Instead, the model is derived within the framework of the limit equilibrium method of slope stability analysis, and accounts for pressure buildup and decreasing cohesion in the slope due to hydrate dissociation. The proposed model is then employed to map the landslide susceptibility of a study area conditioned to a hypothetical scenario of seafloor warming that triggers hydrate dissociation. The susceptible zones are found in the regions with shallow water and high geothermal temperature. Unlike the terrestrial landslides, the slope angle plays a secondary role in affecting the susceptibility of submarine landslides triggered by hydrate dissociation, while the hydrothermal conditions are important factors that control the susceptibility.