Systematic Swath Mapping of the Mediterranean—a Key to Understanding Past and Active Geological Processes

Mascle, Jean Robert¹, Benoit Loubrieu² (1) CNRS Geosciences-Azur, Villefranche sur Mer, France (2) IFREMER Centre de Brest, Brest, France

During the recent years sytematic swath mapping of most of the deep Mediterranean basins (approximately from 500 to 5000 meters water depth) has been undertaken by sev­eral European Institutions, notably from France, Italy, Spain and Greece. In the frame of a cooperation between various academic agencies, these data have been combined in an homogenous DTM, at a 500 meters grid, to provide the first precise geomorphologic maps of the two,geologically contrasted, Western and Eastern, Mediterranean basins. The detailed morphology reveals many characteristics triggered by geological processes operating on the sea bed. These data are also crucial to locate potential submarine geo-hasard areas. Among the results of active processes directly imprinted on the sea floor are: mud constructions, and accompanying fluid seepages (seen on both active and passive margin segments, par­ticularly in Eastern Mediterranean), effects of interfering sedimentary mechanisms such as turbidite systems, mass wasting and/or large scale sedimentary instabilities, results of tec­tonic activity (particularly, but not exclusively, salt tectonic), or of magmatic activities. We briefly review several of these morphostructural features and focuse on the Nile continental margin and the Mediterranean Ridge where they are particularly spectacular. This stresses the importance of systematic swath mapping, which not only allow to obtain precise mor­phologies, but also provides backscatter images of the sea bed. About 70% of the deep mediterranean basins, and of their bordering continental slopes, are now mapped. By now the Mediterranean sea is probably one of the most surveyed world’areas using combined swath bathymetric and backscatter data.