Shallow‐water acoustic measurements in the southern Adriatic Sea

Shallow‐water acoustic and geoacoustic measurements were made in the southern Adriatic Sea in May–June 1995 in combination with detailed oceanographic, geological, and geophysical surveys. Seismic subbotom profiling, narrow‐beam echosounding, and bottom coring results were used to select two shallow water sites with downward refracting conditions for acoustic experiments: (1) a flat seafloor at 90‐m depth with about 1 m of rigid, nongaseous clay over a sequence of laminated clays and (2) a seafloor sloping from 49‐ to 37‐m depth and consisting of soft gaseous mud over laminated clay. Broadband sparker and 180‐g TNT explosive sources were used for propagation and reverberation to a vertical array receiver in addition to cw sources for propagation. Initial results for the deeper water site show frequency‐independent propagation that is consistent with modeled results using geoacoustic parameters extrapolated from coring results. A modification of the Dix method to estimate sediment sound speed versus depth ...