Multiple Multibeam bathymetric datasets in Naples and Salerno Gulfs (Southern Tyrrhenian sea) calibrated through multichannel seismic profiles

Multiple Multibeam bathymetric datasets collected in Naples and Salerno Gulfs have been calibrated by high resolution multichannel seismic profiles. The research project is based on the processing and the interpretation of bathymetric data recorded by the IAMC-CNR of Naples through different types of Multibeam lateral echosoundings. An analytic comparison between one of the automatic methods most efficient for the data processing, i.e. the CUBE and the manual processing of swath packages has been attempted. The efficiency of the algorithm has been tested on complex morphologies, such as the Capri continental slope and the related geological structures occurring in the Salerno Gulf. The Multibeam data processing and interpretation has been carried out for several research projects (D'Isanto, 2007). The first one is the CNR-SGN Convention for the redaction of marine geological maps at the 1:25.000 scale of Naples and Salerno Gulfs (geological maps n. 465 "Procida", n. 466 "Sorrento" and n. 467 "Salerno". The second one is the CARG Project at the scale 1:10.000 of the Campania region (geological maps n. 464 "Ischia", n. 465 "Procida", n. 466 "Sorrento", n. 446-447 "Napoli", n. 484 "Capri", n. 486 "Foce del Sele", n. 502 "Agropoli", n. 519 "Capo Palinuro", n. 520 "Sapri"). The third one is the GEOSED project for the acquisition of bathy-morphological data for the geomorphological and sedimentological study of selected areas of Campania continental shelf (Capri and Ischia islands). The fourth one is the SISTER II oceanographic cruise of morpho-bathymetric acquisition in intermediate and deep sea bottoms through the RESON 8160 Multibeam and finalized to the geological knowledge of the Sorrento continental slope, the Salerno Valley and the northern and southern Sele highs. A fifth project deals with the morpho-bathymetric surveys committed to the CNR IAMC of Naples by the Authority of the Naples harbor for monitoring the marine pollution of sediments. Dedicated software as the PDS2000 (Thales), the NEPTUNE (Merlin) and the ISIS (Triton Elics) have been used for the cartographic restitution of bathymetric data. The bathymetric maps, both contour isobath maps and shaded-relief maps have been interpreted with the aim of reconstructing the main morphological lineaments occurring at the sea bottom, in particular for the Naples Bay canyons, the continental slope off the Sorrento Peninsula, the sedimentary basin of the Salerno Valley and the related depocenters. Bathymetric profiles have been also produced, allowing to distinguish erosional and depositional areas. The correlation of Multibeam data with some significant seismic profiles recorded in Naples and Salerno Gulfs has completed the geological interpretation. The Salerno Valley, bounding the southern sector of the Sorrento Peninsula, represents an useful laboratory for the study of submarine instabilities related to tectonically-controlled slopes. The individuation of the valley and the activity along the rocky slope bounding it are related to the regional normal or strike-slip fault (Capri-Sorrento fault) bounding southwards the Meso-Cenozoic structural high Capri-Sorrento Peninsula. The Salerno Valley is represented by a deep WSW-ENE trending depression, limited northwards by the normal faults down throwing the Mesozoic carbonates of the Sorrento Peninsula and filled by a Plio-Quaternary sequence thick up to 3300 m (Mina 1 well; Agip, 1977). Multibeam bathymetric survey has evidenced the high steepness of the slope and the occurrence of strong erosional processes, partly active, where a dense network of channellised erosional morphologies has been detected. The analysis of seismic reflection profiles has evidenced the tectonic activity of the fault slope as a triggering cause for g