Timing and frequency of large submarine landslides: Implications for understanding triggers and future geohazard

Large submarine landslides can have serious socioeconomic consequences as they have the potential to cause tsunamis and damage seabed infrastructure. It is important to understand the frequency of these landslides, and how that frequency is related to climate-driven factors such as sea level or sedimentation rate, in order to assess their occurrence in the future. Recent studies have proposed that more landslides occur during periods of sea level rise and lowstand, or during periods of rapid sedimentation. In this contribution we test these hypotheses by analysing the most comprehensive global data set of ages for large (> 1km3) late Quaternary submarine landslides that has been compiled to date. We include the uncertainties in each landslide age that arise from both the dating technique, and the typically larger uncertainties that result from the position of the samples used for dating. Contrary to the hypothesis that continental slope stability is linked to sea level change, the data set does not show statistically significant patterns, trends or clusters in landslide abundance. If such a link between sea level and landslide frequency exists it is too weak to be detected using the available global data base. It is possible that controlling factors vary between different geographical areas, and their role is therefore hidden in a global data set, or that the uncertainties within the dates is too great to see an underlying correlation. Our analysis also shows that there is no evidence for an immediate influence of rapid sedimentation on slope stability as failures tend to occur several thousand years after periods of increased sedimentation rates. The results imply that there is not a strong global correlation of landslide frequency with sea level changes or increases in local sedimentation rate, based on the currently available ages for large submarine landslides.