Evidence of a seismic trigger of the Storegga Slide ~8.2ka
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&deg;
  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.