INFOMAR Seabed Survey Acoustic Backscatter (seafloor hardness)

The integrated Mapping for the Sustainable Development of Ireland’s Marine Resource (INFOMAR) programme is a joint venture between the Geological Survey of Ireland (GSI) and the Marine Institute (MI). The programme is the successor to the Irish National Seabed Survey (INSS) and concentrates on creating integrated mapping products to related the seabed. Backscatter is the reflection of waves back to the direction they came from. By analysing the Amplitude of the returning sound wave it is possible to extract information about bottom structure and hardness, allowing for identification of bottom types. The bottom reflectivity properties depend on the hardness and the roughness of the seafloor surface. In simple terms a strong return signal indicates a hard surface (rocks, Gravel), and a weak return signal indicates a soft surface (silt, mud).