Submarine landslides: processes, triggers and hazard prediction

TLDR

Let's gather: Background sentences: - "Huge landslides, mobilizing hundreds to thousands of km 3 of sediment and rock are ubiquitous in submarine settings ranging from the steepest volcanic island slopes to the gentlest muddy slopes of submarine deltas." - "The major hazards related to submarine landslides include destruction of seabed infrastructure, collapse of coastal areas into the sea and landslide-generated tsunamis." - "Most submarine slopes are inherently stable." - "Because of their tsunamigenic potential, ocean-island flank collapses and rockslides in fjords have been identified as the most dangerous of all landslide related hazards." - "Published models of ocean-island landslides mainly examine ‘worst-case scenarios’ that have a low probability of occurrence." - "Areas prone to submarine landsliding are relatively easy to identify, but we are still some way from being able to forecast individual events with precision." Purpose sentences: - "Here, we summarize current knowledge of such landslides and the problems of assessing their hazard potential." - "Monitoring of critical areas where landslides might be imminent and modelling landslide consequences so that appropriate mitigation strategies can be developed would appear to be areas where advances on current practice are possible." Mechanism sentences: - "Elevated pore pressures (leading to decreased frictional resistance to sliding) and specific weak layers within stratified sequences appear to be the key factors influencing landslide occurrence." - (Also from Purpose, Mechanism line: "Here, we summarize current knowledge of such landslides and the problems of assessing their hazard potential." That sentence is also Mechanism? Actually it's labeled Purpose, Mechanism. So it contributes to Mechanism too: summarizing current knowledge and problems of assessing hazard potential. But that is more Purpose.

Abstract

Huge landslides, mobilizing hundreds to thousands of km 3 of sediment and rock are ubiquitous in submarine settings ranging from the steepest volcanic island slopes to the gentlest muddy slopes of submarine deltas. Here, we summarize current knowledge of such landslides and the problems of assessing their hazard potential. The major hazards related to submarine landslides include destruction of seabed infrastructure, collapse of coastal areas into the sea and landslide-generated tsunamis. Most submarine slopes are inherently stable. Elevated pore pressures (leading to decreased frictional resistance to sliding) and specific weak layers within stratified sequences appear to be the key factors influencing landslide occurrence. Elevated pore pressures can result from normal depositional processes or from transient processes such as earthquake shaking; historical evidence suggests that the majority of large submarine landslides are triggered by earthquakes. Because of their tsunamigenic potential, ocean-island flank collapses and rockslides in fjords have been identified as the most dangerous of all landslide related hazards. Published models of ocean-island landslides mainly examine ‘worst-case scenarios’ that have a low probability of occurrence. Areas prone to submarine landsliding are relatively easy to identify, but we are still some way from being able to forecast individual events with precision. Monitoring of critical areas where landslides might be imminent and modelling landslide consequences so that appropriate mitigation strategies can be developed would appear to be areas where advances on current practice are possible.