A refreshing 3D view of an ancient sediment collapse and slope failure

The combined analysis of high-resolution 2D seismics and an industrial 3D seismic data volume from the western Porcupine Basin, offshore SW Ireland, revealed an unusual picture of a buried sediment collapse and slope failure. A proportionally thin (≤ 85 m) but vast (> 750 km2) slab of consolidated sediments started to slide downslope, in the meantime breaking into hundreds of vertically undisturbed blocks, up to 500 m in diameter. The most probably overpressured underlying horizon seems to have liquefied and acted as a slide plane until the excess pore pressure had dissipated. Then – still very early in the slide development – the process stopped, freezing the failure at its initial stage.