Spatial variability of surficial shallow water sediment geoacoustic properties

Abstract

Variability of surficial sediment geoacoustic properties was determined from cores collected at eight shallow-water continental shelf regions in the U.S., Italy and Australia. Highly porous muds found in low energy environments exhibited the lowest range of values in physical and acoustic properties; mixtures of sand and shell found in higher energy environments exhibited the highest range of values. Compressional wave attenuation consistently exhibited the highest variability followed by mean grain size, porosity and compressional wave velocity. Vertical variability was generally greater than horizontal variability for all properties measured. Sediment geoacoustic properties of most coastal marine sediments are controlled by the interaction of biological and hydrodynamic processes. Biological processes tend to dominate in finer sediments, whereas hydrodynamic processes control sediment geoacoustic properties in sandy substrates. Understanding these processes in various environments not only explains the spatial distribution of sediment geoacoustic properties but leads to improvement of predictive geoacoustic models.