In-Situ Acoustic and Laboratory Ultrasonic Sound Speed and Attenuation Measured in Heterogeneous Seabed Sediments: Eel Margin, California
Abstract
We calculated in-situ and laboratory measurements of sound speed and attenuation in seafloor sediments from the shallow water delta of the Eel River, California. This region receives a substantial volume of fluvial sediments that is discharged annually onto the shell. Additionally, high input of fluvial sediments during storms generates flood deposits characterized by thin-beds of variable grain-sizes in water depths between 40 and 90 m. Main objectives of this study were (1) to investigate signatures of seafloor processes on geoacoustics and physical properties, and (2) to evaluate differences between geoacoustics parameters measured in-situ at acoustic (7.5 kHz) and in the laboratory at ultrasonic (400 kHz) frequencies. The in-situ acoustic measurements were conducted between the 60 and 100 isobath. Wet-bulk density and porosity profiles were obtained to 1.15 meters below seafloor (mdsf) using gravity cores of the mostly cohesive fine-grained sediments across and along shelf. Our physical and geoacoustics property measurements from six selected sites on the Eel margin showed (1) Sound speed and wet bulk density strongly correlated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 08, 2000
- Accession Number
- ADA393653
Entities
People
- Kevin B. Briggs
- Michael D. Richardson
- N. L. Frazer
- R. H. Wilkens
- T. J. Gorgas
Organizations
- United States Naval Research Laboratory