Storegga Slide

64°52′N 1°18′E

Position of the slides

The three Storegga Slides were large landslides. They occurred under water, at the edge of Norway's continental shelf,^[1] in the Norwegian Sea. This is between Norway and Greenland, just north of Great Britain.

Height of tsunami wave.^[2]

Storegga tsunami deposits (grey upper layer), bracketed by peat (dark brown layers), taken at Maryton on the Montrose Basin, Scotland

They caused a very large tsunami in the North Atlantic Ocean. About 290 km length of coastal shelf, 3,500 km³ of debris fell.^[3] This is an area the size of Iceland covered to a depth of 34 m (112 ft).

Based on carbon dating of plant material, the latest incident occurred around 6100 BC.^[4]

In Scotland, traces of this tsunami have been found in the Montrose Basin (estuary of the South Esk river), and the Firth of Forth, up to 80 km inland and 4 metres above today's normal tide levels.

For the Ormen Lange natural gas field, the incident has been thoroughly investigated. One conclusion is that the slide was caused by material built up during the previous ice age, and that it would only happen again after a new ice age. This conclusion is supported by scientific studies. Facts and arguments supporting this conclusion were made public in 2004.

It was decided that the development of the Ormen Lange gas field would not significantly increase the risk of triggering a new slide. A new slide would trigger a very large tsunami which would be devastating for the coast areas around the North Sea and the Norwegian Sea.

References

1. Storegga is Norwegian for the "Great Edge"
2. P.C. Marrow, "Seismic Monitoring of the North Sea", Global Seismology Research Group, British Geological Society, HSE, 1992
3. Bondevik, Stein; et al. (2003). "Record-breaking height for 8000-year-old Tsunami in the North Atlantic" (PDF). EOS, Transactions of the American Geophysical Union. 84 (31): 289, 293. Bibcode:2003EOSTr..84..289B. doi:10.1029/2003EO310001. hdl:1956/729. S2CID 129193102. Archived from the original (PDF) on 2011-08-07. Retrieved 2007-01-15.
4. Bondevik S; et al. (2006). "The Storegga Slide Tsunami: deposits, run-up heights and radiocarbon dating of the 8000-year-old Tsunami in the North Atlantic". American Geophysical Union meeting.