Comparison of high-resolution seismic profiles and the geoacoustic properties of Eckernforde Bay sediments

High-resolution seismic profiles of Eckernforde Bay and the adjacent Baltic Sea were collected, and the geoacoustic properties of sediments there were measured. Bulk densities averaged similar to 1.35 g cm(-3) and ranged from similar to 1.2 to similar to 1.7 g cm(-3). Compressional wave velocities in gas-free sediments averaged similar to 1460 m s(-1) and ranged from similar to 1425 to similar to 1555 m s(-1). In nongassy sediments, bulk density variations typically controlled changes of acoustic impedance. Impedance changes were usually too small and closely spaced to be resolved seismically, although, at certain sites, significant impedance changes are far apart enough that they correlate one-to-one with seismic reflectors. Where free gas is present, velocity decreases and wave energy is scattered, causing a prominent seismic reflector.