Submarine Landslides

Abstract

Robust interpretation of geomorphology is a primary method of understanding failure modes, emplacement mechanisms and post-failure modification of submarine landslides. Since high-resolution hull-mounted multibeam systems became widely available in the last 20 years, our understanding of submarine landslides has improved dramatically. Techniques such as 3D seismic and cm-resolution seafloor mapping has revealed both surface and sub-surface geomorphology in unprecedented detail, and we are making rapid advancements towards refining our understanding of the processes that lead to specific geomorphological signatures associated with slope failure. One of the greatest challenges in the geomorphological analysis of submarine landslides is in accounting for post-failure modification processes. As erosional processes, such as gullying, erode the easily recognisable landslide geomorphology, or sediment drape smothers landslide features, it becomes increasingly more challenging to identify where landslides have occurred. In some depositional environments (e.g. a slope basin) the landslide debris may be preserved in the stratigraphy and analysed using 3D data. However, in erosional environments, such as submarine canyons, there is often little or no remaining deposit and interpretation of landslide processes must be based solely on the landslide scar, which is often heavily modified due to the dynamic nature of the canyon environment. Accurate interpretation and quantification of landslide parameters becomes important for determining magnitude frequency for landslide populations, which is a key piece of information for hazard studies.