Spatial variation of sediment geoacoustic properties at the Seabed Characterization Experiment site

The Seabed Characterization Experiment, sponsored by the Office of Naval Research, was carried out 5 March–10 April, 2017 (SBCEX17) on the New England Mud Patch, approximately 100 km south of Martha’s Vineyard. The main SBCEX17 experimental site covers an area of 15 km × 30 km with water depth in the range of 75–80 m. The Sediment Acoustic-speed Measurement System (SAMS) is designed to measure sediment sound speed and attenuation simultaneously over the surficial 3 m of sediments. Sediment sound speed results in the frequency band of 2–10 kHz can be found in an earlier publication (IEEE JOE, doi:10.1109/JOE.2019.2946004). During SBCEX17, SAMS was successfully deployed at 18 sites, which were chosen to be co-located with gravity or piston cores that were collected during the two recent survey cruises in 2015 and 2016. In this talk, our previous results are extended to include both sound-speed and attenuation. The frequency range is widened, and preliminary results for the dependence of sediment sound-speed and attenuation on both range and depth are presented. Sediment geoacoustic properties obtained by SAMS at the 18 sites are compared with historical and recent sediment property surveys giving information on bottom layering, porosity, and grain size. [Work supported by ONR.]