Open AccessMorphology and mechanics of submarine spreading: A case study from the Storegga Slide
Author(s) -
Micallef Aaron,
Masson Douglas G.,
Berndt Christian,
Stow Dorrik A. V.
Publication year - 2007
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006jf000739
Subject(s) - geology , subaerial , submarine pipeline , submarine landslide , slip (aerodynamics) , pore water pressure , geotechnical engineering , submarine , ridge , seismology , petrology , geomorphology , landslide , paleontology , oceanography , physics , thermodynamics
Spreading is a common type of ground failure in subaerial environments. However, this type of mass movement has hardly been documented in submarine settings. In this paper we show that spreading covers at least 25% of the Storegga Slide scar area, a giant submarine slide located offshore mid‐Norway. The morphological signature of spreading is a repetitive pattern of ridges and troughs oriented perpendicular to the direction of movement. Two modes of failure can be identified: retrogressive failure of the headwall and slab failure and extension, both involving the breakup of a sediment unit into coherent blocks. These blocks are displaced downslope along planar slip surfaces. Limit equilibrium modeling indicates that loss of support and seismic loading are the main potential triggering mechanisms. The extent of displacement of the spreading sediment is controlled by gravitationally induced stress, angle of internal friction of the sediment, pore pressure escape, and friction. The resulting block movement pattern entails an exponential increase of displacement and thinning of the failing sediment with distance downslope. Sediment properties explain the remaining spatial variation of ridge and trough morphologies associated with spreading.