SUBMARINE LANDSLIDES IN THE MISSISSIPPI RIVER DELTA.

Systematic side-scan sonar and high-resolution seismic records from the shallow-water offshore areas of the Mississippi Delta have revealed widespread subaqueous slope failures in bottom sediments. These failures have resulted in damage and loss to offshore structures and pipelines. The features occur on slopes with very low inclinations (ranging from 0. 2 degree to 1. 5 degree ) and in water depths of 5-100 m. The types of features include collapse depressions, bottleneck slides, elongate slides and slumps, mudflow gullies, and overlapping mudflow lobes. Although movements include both vertical and rotational displacements, the basic mechanism can be approximated as downslope translation of shallow slabs of debris. This work is pertinent to offshore structures.