Global analysis of relationship between continental margin submarine landslide scarring and sediment shear strength

Abstract:

The relationship between continental margin physiography and submarine slope stability has been extensively studied to better predict locations of elevated geohazard potential. Despite decades of research at regional scales, a global framework for relating margin location and geologic setting to slope stability has not yet been developed. Here we work towards this goal using a machine learning technique that leverages 50 years of ocean drilling data and the recent proliferation of submarine landslide observations mapped via multibeam bathymetry.

We compiled a database of multibeam bathymetry-derived scar fraction, defined as the area of continental margin covered by landslide scarring compared to total area of continental margin analyzed, from nine continental margins and over 3000 individual landslide scar polygons. This database is used to train and validate a machine learning model that is then used to predict scar fraction for the entire world’s continental margins, from shoreline to continental slope toe. Predicted scar fraction provides a first-order estimate of geologically recent (~100 ky-1 Ma) slope instability at a global scale, a significant advancement over previous studies confined to individual continental margins or smaller.

Predicted scar fraction is compared to sediment shear strength gradient over the top 100 m of subsurface sediments, measured from scientific ocean drilling data at over 100 locations. Trends were analyzed in terms of margin configuration and location, i.e. convergent, transform, passive, hotspot, polar, tropical. These results serve as an important step in assessing the slope stability, and associated geohazard risk, for continental margins at a global scale, especially in data-limited regions such as the Arctic and southern hemisphere.