Underwater Mass Wasting

Submarine landslides play an important role in shaping marine landscapes and pose a major risk to coastal and submarine infrastructure such as pipelines and telecommunications cables. In some cases, submarine landslides have generated tsunamis that have caused widespread damage to coastal communities. Submarine landslides occur in different settings worldwide, including passive, active, and transform margins, river-fed pro-deltas and submarine fans, fjords, as well as the flanks of oceanic islands. Landslides under water are also widespread in lakes and share many similarities with landslides in the oceans. “Subaqueous landslide” is a broader term describing all types of underwater landslides and is currently a major research focus. Characterizing and monitoring submarine landslides is however difficult and relies on remote sensing techniques in water. As electromagnetic waves hardly penetrate through water, sound waves are the only means of surveying subaqueous landslides with reasonable accuracy. This chapter introduces techniques for remote sensing of subaqueous landslides, first with well-established methods focused on mapping headwall areas and deposits and second with more recent repeated surveys and submarine geodetic techniques.