Morphology of small-scale submarine mass movement events across the northwest United Kingdom

A review of multibeam echo sounder (MBES) survey data from five locations around the United Kingdom northwest coast has led to the identification of a total of 14 separate subaqueous mass movement scars and deposits within the fjords (sea lochs), coastal inlets and channels between the islands of the Inner Hebrides. In these areas sediment deposition was dominated by glaciomarine processes. Analysis of the morphometric parameters of each submarine mass movement has revealed that they fall into four distinct groups of subaqueous landslides; Complex (translational & rotational), Multiple Single-Type, Singular Slumps, and Singular Translational failures. The Complex (translational & rotational) Group included landslides that exhibited complex styles of failures, including both translational and rotational mechanisms influencing the same slide, whereas the Singular Translational Group only included a single slide (Holy Loch Slide) that displayed characteristics associated with translational (planar) failure only. Similarly, the Multiple Single-Type Group incorporated scars and deposits that displayed morphometric features consistent with the amalgamation of several failure events of the same type (e.g. debris flows or slumps), compared with the Singular Slump Group which included discrete, individual subaqueous slumps that exhibited no evidence of modification through merging of several scars. It is acknowledged that additional MBES data are needed to expand this database, in order to create a more statistically robust study, however this initial study provides the basis for a much wider investigation of subaqueous mass movements and correlations between their morphometric parameters.