Stad Slide: Preconditioning and failure of one of the world's largest megaslides

ABSTRACT Submarine landslides can generate tsunamis and pose risks to underwater infrastructure, but a lack of direct observations of such slides hinders our understanding of their development and hazard potential. Studying the morphology of past slides can offer insights into their preconditioning and failure. Here, new high‐quality 2D and 3D seismic data were used to determine, for the first time, the extent and morphology of the Stad Slide (~0.4 Ma) on the northeast Atlantic margin. With a volume of ~4300 km 3 and a maximum thickness of ~360 m, we reveal that this slide is the largest by volume on the proximal North Sea Fan and amongst the largest known megaslides globally. Its large volume was likely facilitated by retrogressive development along layers of glacimarine and contouritic sediment. The broad timing of the Stad Slide aligns with enhanced glacial sedimentation in this region, which is likely to have preconditioned failure by increasing overpressure in underlying sediments. The slide headwalls are infilled by an ~200 m‐thick contourite drift that may have formed the weak layer for subsequent sliding on the North Sea Fan.