Novel Method to Map the Morphology of Submarine Landslide Headwall Scarps Using Remotely Operated Vehicles
Submarine landslides are one of the main marine geohazards worldwide. In order to better estimate their risk and develop mitigation measures, a better understanding of the failure mechanisms is needed. However, observing landslides in real time is near to impossible, hence careful study of both the failed sequence and the deposit is still the main source of information. Until recently, studies of the headwall scarps of submarine landslides were mainly based on shipboard acoustics and the descriptions of analogues on land. The increasing availability of Remotely Operated Vehicles (ROVs) now allows in-situ, close-up investigations in the marine environment. In this paper we present a novel methodology to obtain a detailed map of the headwall morphology of submarine landslides, including detail on vertical cliffs, overhanging strata and biological colonisation. Using a high-resolution multibeam system mounted on the front of a working-class ROV, rather than in a traditional downward looking configuration, we mapped three sections of a scallop-shaped headwall scarp which is part of the Rockall Bank Slide Complex, west of Ireland, as part of the SORBEH cruise funded by the Irish Government and the ERC CODEMAP project. The resulting 3D model provides insights in the build-up of the failed sequence, allowing advances in the understanding of rupture mechanisms. It can be combined with close-up video ground-truthing and carefully collected samples to create a complete picture of the headwall scarp.
KeywordsAutonomous Underwater Vehicle Submarine Landslide Volcanic Cone Vertical Cliff Point Cloud Model
The SORBEH expedition (‘Slope collapses On Rockall Bank and Escarpment Habitats’) was supported by the Irish Marine Institute and was funded under the Marine Research Sub-Programme by the Irish Government. VH is holder of the ERC Starting Grant CODEMAP (‘Complex Deep -sea Environments: Mapping habitat heterogeneity As Proxy for biodiversity’, Grant number 258482), which co-funded the vertical mapping exercise. The authors would like to thank the cruise-organising team in the Marine Institute, the captain and crew of the RV Celtic Explorer, and the ROV engineering team, especially Patrick O’Driscoll and Will Handley for making this work possible. We are very grateful to Terje Thorsnes and John Hughes Clarke for their helpful and supportive reviews.
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