What type of undersea event was the prehistoric Storegga Slide?

The prehistoric Storegga Slide was a submarine landslide.

Storegga refers to a series of enormous underwater landslides that occurred along the edge of Norway’s continental shelf in the Norwegian Sea. The failures moved vast amounts of sediment downslope beneath the sea, making them submarine landslides rather than volcanic eruptions, meteor impacts, or coral collapses.

The largest event occurred roughly 8,000 years ago, during the early Holocene. Geological evidence indicates that the slides displaced around 3,500 cubic kilometers of material across a shelf margin extending for hundreds of kilometers. The sudden movement of the seafloor generated a powerful tsunami across the North Atlantic.

That tsunami left sediment deposits in parts of Norway, Scotland, England, and elsewhere. It may also have helped flood Doggerland, the low-lying landmass that once connected Britain with continental Europe, although the timing and precise contribution of the Storegga tsunami remain subjects of scientific study.

“Submarine landslide” describes the event itself; the tsunami was the major consequence produced by the underwater collapse.