9

The Storegga Slide was a catastrophic underwater landslide that occurred off the coast of Norway about 8,200 years ago. This YouTube clip shows simulations that indicate that this slide resulted in landslides in the 10's of metres across the surrounding shorelines, including the Norwegian coast, Greenland, Iceland, Shetlands, Orkneys, Britain etc and by several accounts, it wiped out the now submerged North Sea land-bridge known as Doggerland.

A possible cause from the Wikipedia article (linked above) is:

A likely triggering mechanism is thought to be an earthquake causing a catastrophic expansion of methane hydrates.

This earthquake scenario is also mentioned in this YouTube clip.

What evidence is there of a seismic trigger of the Storegga Slide?

  • As I see it, cause and triggering mechanism are different things. The cause behind the landslide is the large sediment input on the Norwegian shelf that creates an unstable system. There are a number of similar submarine land slides along North Atlantic shelf edge that might be related to glaciation and the Cenozoic uplift. See e.g. Evans et al (2005) – user2821 Aug 12 '15 at 12:36

1 Answers1

7

Scandinavia experienced a lot of earthquakes due to post glacioisostatic rebound 10 - 7 ka. The most likely trigger for the Storegga Slide was a strong earthquake or a series of earthquakes. However, large sediment input from glaciation rather than earthquakes are the causes of the unstable slope. Release of overpressured gas hydrates was the driving force for the violent development of the slide.

It is reasonable to relate the period with strong earthquakes with rapid rebound and the triggering of the Storegga Slide. Recent modelling shows that the seismic energy can induce ground shaking that lasts longer than previously assumed in the deep sedimentary Møre basin (Lindholm et al., 2005). In the Storegga region the isostatic deformation and reactivation of Late Jurassic–Early Creteaous faults because of sediment loading on the North Sea Fan probably caused an elevated earthquake level. [...] The combined effects of excess pore pressure, exposure of ooze, relative steep slopes 10–20° and to the vicinity of potential earthquake centres favour an initial slide in the distal area.

Bryn et al. (2005)

  • Bryn, P., et al. "The Storegga Slide complex; repeated large scale sliding in response to climatic cyclicity." Submarine mass movements and their consequences. Springer Netherlands, 2003. 215-222.
  • Bryn, P., et al. "Explaining the Storegga slide." Marine and Petroleum Geology 22.1 (2005): 11-19.
  • Lindholm, C., et al. "Probabilistic and deterministic seismic hazard results and influence of the sedimentary Møre Basin, NE Atlantic." Marine and petroleum geology 22.1 (2005): 149-160.
  • Berndt, C., et al. "Submarine slope-failure offshore Norway triggers rapid gas hydrate decomposition." 4th int. conf. on gas hydrates proc., Yokohama, Japan. 2002.
  • Bungum, H., Lindholm, C. and J. I. Faleide. "Postglacial seismicity offshore mid-Norway with emphasis on spatio-temporal–magnitudal variations." Marine and Petroleum Geology 22.1 (2005): 137-148.
user2821
  • 5,946
  • 2
  • 28
  • 54