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

Abstract

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 km2. 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.