R/V OGS Explora
The
CUMECS-2 survey will be carried out using the R/V OGS
Explora, which is a 72.6 m multi-purpose research vessel operated by the Istituto
Nazionale di Oceanografia e di Geofisica Sperimentale.
Multibeam
echosounder
Bathymetry
data constitute the main source of information on the morphology of the
seafloor. Bathymetric maps are typically compiled using a multibeam echosounder
mounted undearneath the research vessel. Seafloor depth is estimated by
measuring the time it takes for a beam of sound to travel from a sounder to the
seafloor and be reflected back to the sounder. The echosounder features tens of
narrow adjacent beams arranged in a fan-like swath 90° - 180° across. The beams
update many times a second, allowing a wide coverage of the seafloor and
generating bathymetric maps and digital elevation models, as well as maps of
the intensity of the acoustic response (known as backscatter) that provide
information on seafloor composition.
High resolution seismic reflection profiling
Reflection seismics is a technique that provides information about the subsurface structure of the seafloor. The general principle involves sending artificially generated acoustic waves down the water column and into the seafloor, where the different structures and objects reflect this energy back according to their acoustic impedance. These reflected energy waves are recorded and processed to produce a visual representation of the seabed subsurface.
Gravity coring
Gravity coring is a simple but effective method to obtain sediment from the seafloor. A gravity corer consists of a weight connected with a 6 m long steel tube. The end of the gravity corer is fitted with a cutter section and a catcher to retain the sampled material. The corer is lowered to the seafloor using a long wire and is stopped at a set distance above it. The corer is then lowered at a set speed into the sediment, after which it is raised to the surface and the sediment is recovered.
