IN SITU DIRECT MEASUREMENTS OF SEDIMENT COMPRESSIONAL AND SHEAR WAVE PROPERTIES IN CURRITUCK SOUND AND COMPARISON TO THEORY

摘要

The geophysics of low frequency sound in extremely shallow water is not well understood, which limits practical applications. When the water depths are on the order of a few acoustic wavelengths, bottom properties are expected to strongly influence sound propagation in the water column. In an effort to characterize the bottom in such an environment, this paper reports direct in situ measurements of compressional (sound) and shear wave speed and attenuation collected below the water-sediment interface in Currituck Sound, a shallow protected inlet on the Outer Banks of North Carolina, USA. Three measurement locations having distinctly different sediment types are discussed: (1) a near-shore site with medium-grained sand, (2) an offshore shallow water site with fine-grained sand, and (3) a deeper offshore site with muddy fine-grained sand. Varying amounts of biological material, including marine plants and their root systems, were present at all sites although they were most prevalent near the shore.