In-Situ Acoustic and Laboratory Ultrasonic Sound Speed and Attenuation Measured in Heterogeneous Seabed Sediments: Eel Margin, California
NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
Pagination or Media Count:
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.