Acoustical techniques for observing the processes that control the formation of ocean bottom geology

Abstract

While acoustical methods provide useful techniques for surveying geological properties of the seafloor, acoustical techniques are also useful for examining the processes which create the observable geological properties. The dynamic processes which control sediment deposition and erosion are complex, and understanding these processes requires knowledge of the interactions of the seafloor topography with the hydrodynamics just above the seafloor and the subsequent sediment erosion, transport, and deposition. Observing these interactions requires multi-dimensional systems with high resolution in both space and time. This mini-tutorial talk will review some of the acoustic techniques for observing sediment transport processes which are currently being used. These techniques include acoustic backscatter measurements of suspended sediment concentration, acoustic imaging techniques such as rotary sidescan sonars and rotary pencil beam sonars, and the latest advances in high-resolution Doppler current profiling. Examples of data from these techniques will also be presented to give an overview of the transport processes including sediment transport due to the combined action of both waves and mean currents, sediment transport due to gravitational flows, and the relation between bedform migration and bedload transport.