Numerical Imaging of the Seabed and Acoustic Flares with Topography and Velocity Variance

Abstract

During seabed mapping, anomalous acoustic events in the seawater layer often degrade bathymetric quality. Acoustic-flare-like events that are induced by gas seepage occur accompanied by small seabed depressions known as pockmarks. In this study, we performed numerical imaging to verify whether acoustic flares are related to changes in the topography of the seabed. The input models assumed convex or concave upward structures which differ based on aperture size. The imaging study determined that acoustic flares appear because the sensing instrument measures the velocity changes in the water layer regardless of the seabed topography. Changes in the velocity of the seawater column can be caused by the concentration of suspended particles and the wave current above the seabed, but further quantification research is required.