Sedimentology, geotechnical properties and stability of the surficial sediments on the continental slope, southwestern Flemish pass

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Abstract
This study describes the sedimentology and geotechnical properties of the surficial sediments on the continental slope, southwestern Flemish Pass. The continental slope has a gradient ranging from 0.06° to 2.3°. The sediments are of late Wisconsinan to Holocene in age and are characterized by marked subsurface grain‐size textural changes. These textural changes reflect differing sedimentation styles, e.g., terrigenous slope sedimentation, catastrophic debris flows, turbidities, and ice‐rafted detritus. Geotechnical analysis include microscopy, X‐ray analysis, water and carbonate contents, index properties, clay mineral analysis, undrained shear strength, and consolidation tests. The stability of the slope sediments is examined in terms of the infinite slope stability model using the above mentioned geotechnical data and the sea floor gradient. The traditional model has been improved to take into consideration the effective pressure and the liquefaction potential of the sediments under earthquake loading. With an average maximum slope gradient of 2.3° on the flanks of the Pass, the deeper, lower normally consolidated sediments of the soil profile will remain stable under a seismic horizontal acceleration of up to 0.20 g. The stability of the upper sediments needs further investigation and more refined testing.