Storegga slides
-
What are the Storegga slides?
The Storegga slides were a series of undersea landslides in the Norwegian Sea that took place roughly 8,400 to 2,200 years ago. The resulting scar, identified in 1983, is considered by geologists to be the largest area of slope failure on Earth.
Spanning approximately 95,000 square kilometers, the scar contains between 2,400 and 3,500 cubic kilometers of sediment. The primary landslide, which occurred approximately 8,400 to 7,800 years ago, coincided with a major tsunami that impacted coastal areas bordering the Norwegian and North Seas.
Scientists hypothesize that undersea earthquakes weakened the continental shelf's headwall, triggering the shelf's collapse. Another hypothesis suggests that the rapid release of methane gas, trapped as gas hydrates in seafloor sediments after the last ice age, either triggered the landslide or contributed to the destabilization of the headwall.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What is a submarine landslide?
A submarine slump is a relatively rapid, sporadic downslope movement of sediment and organic debris that accumulates into an unstable mass in a submarine canyon or on a continental slope.
The Storegga slides are a series of submarine landslides that occurred in the Norwegian Sea between 8,400 and 2,200 years ago. These slides created a large scar on the seafloor, which extends approximately 1,600 km into the abyssal plain of the Norwegian Sea. The scar covers an area of about 95,000 square km and contains 2,400–3,500 cubic km of sediment. Some scientists believe that tsunamis caused by the Storegga slides washed away the land bridge connecting Great Britain and continental Europe.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Where did the Storegga slides occur?
The Storegga slides, a series of underwater landslides, took place in the Norwegian Sea between approximately 8,400 and 2,200 years ago. The scar from these slides starts about 100 km (60 miles) off the More Coast of Norway, at the edge of Europe's continental shelf, and stretches around 1,600 km (1,000 miles) into the Norwegian Sea's abyssal plain.
The resulting scar covers roughly 95,000 square km (about 36,700 square miles) and holds 2,400–3,500 cubic km (576–840 cubic miles) of sediment. Some scientists believe that tsunamis from the Storegga slides washed away the land bridge connecting Great Britain to continental Europe.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What caused the Storegga slides?
The Storegga slides were a series of underwater landslides in the Norwegian Sea that took place roughly 8,400 to 2,200 years ago. The resulting scar, identified in 1983, is considered the largest area of slope failure globally.
While the exact cause is debated, most scientists suggest that undersea earthquakes weakened the continental shelf's headwall (the steep, rising slope). Another hypothesis is that the rapid release of methane gas, trapped as gas hydrates in seafloor sediments after the last ice age, either triggered the landslide or destabilized the headwall.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What were the effects of the Storegga slides?
The Storegga slides were a series of underwater landslides in the Norwegian Sea between 8,400 and 2,200 years ago, creating the largest known area of slope failure on Earth.
The slides generated tsunamis that left sand deposits in the Shetland and Orkney Islands, the coast of eastern Scotland, and parts of England's northwestern coast, reaching up to 80 km inland and 6 meters above normal tide levels. Some scientists believe that a tsunami linked to the slides washed away the land bridge connecting Great Britain to continental Europe.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How did the Storegga slides create tsunamis and what areas were affected?
The Storegga slides were a series of underwater landslides in the Norwegian Sea that occurred between 8,400 and 2,200 years ago. These slides generated tsunamis due to the sudden displacement of a large volume of water. The scar, identified in 1983, is considered the largest area of slope failure in the world.
The tsunamis impacted coastal areas bordering the Norwegian and North Seas. Sand deposits attributed to these tsunamis have been found in the Shetland Islands, the Orkney Islands, the coast of eastern Scotland, and parts of England’s northwestern coast, reaching up to 80 km inland. Traces of tsunami-delivered sediment also appear in Iceland, Norway, and the Faroe Islands. Models suggest that tsunami waves reached heights of 20–25 meters along the coast of the Shetland Islands, 10–12 meters along the Norwegian coast, and 5 meters along the coast of eastern Scotland.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Storegga slides, series of submarine landslides in the Norwegian Sea that occurred between approximately 8,400 and 2,200 years ago. The combined activities of these landslides produced a scar on the seafloor that begins some 100 km (60 miles) off Norway’s More Coast on the edge of Europe’s continental shelf and extends some 1,600 km (1,000 miles) into the abyssal plain of the Norwegian Sea. Geologists regard the scar, which was identified in 1983, as the largest area of slope failure in the world. Some scientists contend that one or more tsunamis associated with the Storegga slides washed away the land bridge connecting the island of Great Britain with continental Europe. Storegga is the Old Norse word meaning “great edge.”
The scar caused by the slides spans an area of approximately 95,000 square km (about 36,700 square miles) and contains 2,400–3,500 cubic km (576–840 cubic miles) of sediment. Most geologists maintain that nearly the entire volume of the scar was the result of a landslide that took place approximately 8,400–7,800 years ago. The timing of this event coincides with a catastrophic tsunami that affected several coastal areas bordering the Norwegian and North seas. Two relatively minor landslides, which occurred between about 5,700 and 2,200 years ago, followed this event. Other geologists argue that the scar is the result of at least three moderate-sized tsunami-producing landslides that occurred between 50,000 and 6,000 years ago.
Sand deposits attributed to the tsunamis triggered by one or more of the Storegga slides occur in the Shetland Isles, the Orkney Islands, the coast of eastern Scotland, and parts of England’s northwestern coast. Some deposits extend up to 80 km (about 50 miles) inland and 6 metres (20 feet) above current normal tide levels. (The sea level at the time was 14 metres [46 feet] lower than at the present day.) Traces of tsunami-delivered sediment also occur in Iceland, Norway, and the Faroe Islands. Some models of the Storegga slides estimate that tsunami waves exceeded 20–25 metres (65–80 feet) in height along the coast of the Shetland Islands, 10–12 metres (33–39 feet) along the Norwegian coast, and 5 metres (16 feet) along the coast of eastern Scotland.
Although there are a number of hypotheses concerning the cause of the shelf’s collapse, most scientists believe that a series of undersea earthquakes weakened the headwall (the steep, rising slope) of the continental shelf. Other scientists contend that the rapid release of methane gas trapped as gas hydrates in seafloor sediments deposited after the most recent ice age may have triggered the landslide outright or contributed to the destabilization of the headwall. Some studies note that parts of the edge of the continental shelf in the region bordering the scar are not stable, and companies involved in petroleum and gas exploration continue to exercise great care in order to prevent another slide.
Between 9,000 and 7,000 years ago, rising sea levels began to separate Great Britain from the landmass of continental Europe by inundating parts of the Dogger Land Bridge, which linked Great Britain with Denmark and the Netherlands and spanned what would become the southern part of the North Sea. This region, which is colloquially referred to as “Doggerland,” was inhabited at the time by humans, who slowly abandoned the area as sea levels rose. Some scientists contend that the tsunami caused by the landslide that occurred 8,400–7,800 years ago washed away the remaining land connections between Great Britain and the continent, leaving a small shoal known as the Dogger Bank just below the surface of the North Sea.