A numerical investigation of excess pore pressures and continental slope stability in response to ice sheet dynamics

Submarine landslides are common at glaciated continental margins. The onset of large-scale landslides coincides with the initiation of Northern Hemisphere glaciations in the Quaternary. This implies that processes related to glacial cycling provide favourable conditions for submarine landslides at high-latitude margins. Potential processes include glacial deposition patterns and enhanced seismicity. It is also possible that advances and retreats of ice sheets, a highly dynamic process in geologic terms, makes slopes discernible to failure by modifying the stress regime. Here, we quantify this effect using 2D Finite Element modelling of a glaciated continental margin. Different model runs investigate the pore pressure development in homogeneous as well as layered slopes during glaciation when loaded by an ice stream with one or multiple ice advances. Ice streams cause significant variations in excess pore pressure in the very shallow sediment sequences at the continental shelf. However, lateral fluid flow is not efficient enough to increase pore pressures significantly at the slope, where large-scale submarine slides are observed. Hence, while ice sheet dynamics appear to favour the occurrence of shallow slides close to the shelf edge, ice sheets seem to be irrelevant for the generation of large-scale submarine landslides at the continental slope.