Characterisation of weak layers, physical controls on their global distribution and their role in submarine landslide formation

Submarine landslides pose a hazard to coastal communities as they can generate powerful tsunamis, and threaten critical offshore infrastructure such seafloor cable networks that underpin global communications. Such events be orders of magnitude larger than their onshore equivalents. Despite the pose, many aspects submarine remain poorly understood, why fail on low angle (<2°), seemingly stable slopes. Many studies have proposed failure slope angles, large areal extent landslides, may controlled by presence laterally-extensive weak layers embedded within stratigraphy, which precondition slopes failure. Little remains known, however, about characteristics processes control form layers. We conducted comprehensive review published landslide examine planes apparent associated with historical ancient landslides. Based new catalogue comprises 64 case studies, this aims investigate types sediment understand controls variability. Existing classification schemes are based mechanical process(es), do not readily enable diagnosis from unfailed sediments. Here, complementary lithology is introduced. This enables layer recognition cores (including those sampling sediments), allows us attribute mechanisms different environmental settings where distinct more likely. The results show usually in vicinity an interface between lithologies together comprise layer. 22 were related characteristic sequences 19 classified direct measurements in-situ measurements: 16 siliciclastic, four volcaniclastic, two fossiliferous sequences. Only three landsides clay-dominated In addition, along lithological contrasts was inferred for six studies. depositional models likely locations these inferred. These include oceanic gateways long-term circulation create permeability interfaces siliciclastic sequences, areas high productivity biogenic sediments dominate, regions experience widespread ash fall volcanic eruptions. highlight historically collected characterise intact sedimentary instead focused characterising deposit. As collapse or become heavily modified during failure, there omission key information required geotechnical analysis determine certain predisposed conclude highlighting need combine detailed sedimentological geophysical analyses including grain-scale observations (e.g. micro-Computed Tomography 3D imagery), emphasise importance uniform workflow will allow better comparison individual