Seafloor and near‐surface sound velocities from Barents Sea sonobuoy data

Abstract

The uppermost identifiable head waves from the vicinity of the seafloor andgroup velocities developed from multiples of critical reflections are utilized to contour sound velocities from near the floor of the Barents Sea, an area with divergent velocity structures. Where the low‐velocity sediments are 30 to 80 m thick and cap relatively high‐velocity materials, the seafloor sound velocities determined from critical reflections are strongly dependent on frequency. Multiple reflections from thick‐layered sediments, without major velocity discontinuities, are not affected by passbands that vary from 15–40 up to 100–200 Hz. Certain sonobuoy records are compared with wave equation solutions at fluid/solid and solid/solid interfaces modeled from the Barents Sea data. Results indicate that the presence of quite thin sediments (∼30 m), not otherwise detectable, may be required to account for the behavior of p waves from apparently high‐velocity seafloors. Under the fairly restrictive conditions of a fluid/solid interface, shear wave velocities can be estimated from the pattern of reflected p wave energy.