Giant pockmarks discovered on the West Greenland shelf

Pockmarks provide valuable insights into subsurface fluid dynamics, methane release, and potential geohazards. We present the first detailed mapping and characterization of giant pockmarks (>250 m diameter) on the West Greenland continental shelf using high-resolution multibeam bathymetry and supporting seismic data. A total of 42 giant pockmarks, circular to elliptical in shape, were identified across five deep-water troughs in the Disko, Uummannaq, and Melville regions, mostly at depths >460 m. The Disko Trough contains both the highest concentration and largest features (max 800 m diameter), together with smaller pockmarks with morphologies and seismic expressions suggesting recent seepage. Diagnostic criteria are provided to distinguish iceberg keel features (ploughmarks and impact pits) from fluid-escape structures. We propose hypothetical formation mechanisms in which giant pockmarks formed—during or shortly after deglaciation—through combined effects of isostatic rebound linked to rapid ice retreat, sediment loading, and ocean warming—processes likely to trigger gas-hydrate dissociation and overpressure-driven fluid escape. Clustering of giant and smaller pockmarks near coastal geological boundaries and faults further suggests a neo-tectonic influence on gas/fluid migration. These findings reveal the distribution, morphology, and likely formation processes of giant pockmarks on the West Greenland margin and highlight their geohazard significance.