Geologic features at the continental shelf edge and their influence on acoustic propagation and scattering

Abstract

The continental shelf edge, encompassing the seaward edge of the continental shelf and the upper continental slope, is a region of significant variation in the physical, chemical, and biological character of the ocean and seabed. The surficial and shallow sub-surface geologic features across this transition from the seaward-dipping shelf to the steeper upper slope reflect a spectrum of modern and antecedent constructional and destructional processes, each affecting acoustic propagation and scattering. Geologic features across the shelf edge are created by eustatic and regional sea level change, glacial processes, development and abandonment of fluvial pathways, and variations in slope stability. These geologic features are further modified by seasonal and persistent water column and bottom-water boundary layer physical processes, diagenetic modification, and biological activity supported by nutrient rich upwelling. Using examples from the southern New England shelf edge (SNESE), the scale, morphology, formative processes of shelf edge features and their impact on acoustic propagation and scattering will be presented. The SNESE has been shaped by a combination of glacial and interglacial processes resulting in a region with a complex seabed environment characterized by features such as variable surficial sediment, pockmarks, landslide scars, and submarine canyons. [Work supported by the Office of Naval Research.]