Two different sediment types were involved in the Storegga Slide. Marine clay sediments show contractive behaviour, and glacial deposits (tills and glacial debris flow deposits) were observed to be dilatant. In this study, the steady state concept is used to interpret the behaviour of the sediments in the Storegga Slide. Disintegrative failure took place in the marine sediments with a positive state parameter, and non-disintegrative failure occurred in the glacial deposits with a negative state parameter. This provided a favorable condition for long run-out distances of the material along the marine sliding planes during the post-failure stage and limited displacement in some parts of the Storegga Slide in glacial deposits.