Submarine landslides triggered by iceberg collision with the seafloor

Iceberg discharge influences ocean circulation, affects climate and increases global sea level. Icebergs are also known to gouge the seafloor in water depths limited by their keel depth, thus representing a hazard to subsea infrastructure. Here, we provide evidence that icebergs can affect the seafloor at depths greater than their keel depth by triggering submarine landslides. Using repeat bathymetric surveys from multibeam echo sounders, we investigate the cause of a submarine landslide that occurred in Southwind Fjord, Baffin Island, between September 2018 and September 2019. This landslide is shown to be closely associated with recently formed iceberg pits at its headscarp carved by an iceberg that grounded and that capsized in the fjord in early September 2018. Geotechnical data from a nearby sediment core indicate that the vertical loading induced by the iceberg grounding and capsizing is sufficient to trigger the observed landslide. These results imply that icebergs originating from the Arctic, Greenland and Antarctica are hazards thousands of kilometres away from their original source and can affect continental slopes by triggering submarine landslides. This process represents an additional source of marine geohazards, especially if climate change leads to increased iceberg discharge. Iceberg gouging of continental slopes can initiate submarine landslides, potentially far from the iceberg source region, according to observations and geotechnical analysis of an event in a Baffin Island fjord.