Structure and morphology of submarine slab slides: Clues to origin and behavior

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Abstract
Submarine slab slides occur in homoclinal sections of consolidated sediment and lithified strata on continental and insular slopes. They are characterized by distinctive structural and morphological features including complex scarps, sheet‐like or tabular form, proximity to intrastratal deformation, and highly comminuted, long‐runout debris sheets having distinct margins and flow forms. Such slides are difficult to explain by conventional concepts of slope stability that depend on Mohr‐Coulomb failure criteria unless conditions of very low effective stress are invoked. Geologic features suggest that some slab slides probably result from long‐term strength degradation of weak layers deep in the homoclinal section. Time‐dependent strain in clay‐rich layers can create potential slide surfaces of low factional strength. Competent layers are weak in tension and probably fragment in the first instance of, or even prior to, translation, and the allochthonous mass is readily transformed into a high‐momentum debris flow. The structure and geomorphology of slab slides provide important clues to their origin and behavior. Proper consideration of geological features and stress history of a failed homoclinal section can help determine the most likely mechanism of failure and the most useful model of kinematic behavior of slab sides.