Normal-incidence bottom loss measurements over a sand-mud gradient and comparison to direct seabed measurements

• DOI: 10.1121/10.0008552
• Publication Date: 2021-11-18T23:56:11Z
• Authors: Kevin M. Lee; Megan S. Ballard; Gabriel R. Venegas; W. Cyrus Clemo; Kelly M. Dorgan; Nick Brilli; Nina Stark; Joseph Calantoni
• Keywords: Penetrometer; Seabed; Speed of Sound

Seabed variability introduced by physical or biogenic processes contributes to multi-scale horizontal and vertical in seabed acoustic geotechnical properties. An experiment was conducted near the mouth of Mobile Bay investigate such spatial over a mud-sand gradient. A normal-incidence bottom loss survey on 750 × 1500 m2 grid with 50-m track-line spacing, which broadband source transmitted frequency-modulated chirps (1–100 kHz) every second, resulting dense sampling reflection coefficient wide frequency band. Diver cores were collected area for direct analysis near-surface Cores acoustically logged obtain profiles sound speed attenuation (10–1000 then analyzed properties (porosity, grain size, carbon content), infauna community composition, sediment strength Additionally, situ portable free fall penetrometer measurements within characterize upper 50 cm sediment. Spatial distributions estimated from (e.g. porosity speed) will be compared examine potential connections between acoustic, geotechnical, biological parameters. [Sponsored ONR.]