Echo-character distribution in the Cantabrian Margin and the Biscay Abyssal Plain

In 2003, 2006-2009, 2014 and 2015, seven oceanographic cruises were carried out on board the Spanish R/V Hespérides in the Cantabrian Margin and the adjacent abyssal plains, covering an area of 219,124 km 2 . Based on the combined analysis and interpretation of the bathymetric and reflectivity data obtained with multibeam echo sounders (SIMRAD EM12, EM120 and EM1002), and ultra-high-resolution reflection seismic records acquired with the SIMRAD TOPAS PS18 parametric sounder, the mapping of the acoustic facies or echo-character at a scale of 1:1,200,000 has been carried out. Thirty types of echoes have been differentiated and gather into four main groups: Distinct, Irregular, Hyperbolic and Undulated. The echo-character depends on the acoustic response of the shallow sediment and the seabed morphology. Therefore, its analysis and characterization are basic for understanding recent and present-day sedimentary processes.