Hydrographic (geophysical and geotechnical) survey offshore : Viana do Castelo (Phase I)

Abstract

By WAVEC's request, the Instituto Hidrográfico carried out the seabed mapping and characterisation of the ZLT off Viana do Castelo considering two phases: 1) description of the geomorphology and structure of the recent sedimentary layer and 2) characterization of geotechnical properties of the sedimentary layer and high-resolution acoustic mapping. This report presents the work carried out in the first phase and includes the description of the geomorphology, the structure of the sedimentary cover and the remote characterization of the seabed. The work started with two oceanographic surveys that enabled acoustic data and samples to be collected. The fieldwork took place in March 2023, on board the NRP "D.Carlos I", and in October 2023 on board the NRP "Andrómeda". The final results show a sedimentary morphology and structure strongly conditioned by the geological setting of the area and the influence of oceanographic factors. The unconsolidated sedimentary cover is, in general, relatively homogeneous with two main sedimentary units being identified, deposited on a rocky substrate that outcrops in small areas in the SW corner of the area