Study of the subsoil of the coastal urban area of Bagnoli-Fuorigrotta (Naples, Italy)

From different years the attention of the scientific world is turned toward the study of coastal urban areas as important poles of urbanistic development. Particular attention has been turned in the city of Naples, whose municipality is working in the attempt to revise and to develop its coastal areas previously destined to an industrial use, as the eastern zone of the Naples's harbour and San Giovanni to Teduccio to east, and the ex area of the ILVA of Bagnoli to west. The revision of these coastal areas needs one examined thoroughly geological knowledge also of the subsoil, both inshore and offshore, this because the principal present infrastructures are often found to horse among these two areas, as for example the mooring piers, the docks and the harbours -channel. The Bagnoli-Fuorigrotta area, destined to tourist revision, also thanks to the presence of hydrothermal springs, has been object of a long study on our part. Particularly a detailed reconstruction of the subsoil is effected, both in the Bagnoli-Fuorigrotta Plain, that in the bay in front, for a distance of about a kilometre and a half. For the study of the inshore subsoil a data base more of 100 wells of several origin has been used; while for the study of the offshore area two reflection seismic profiles have been used, located to a distance of about a kilometre from the coastline and that cover a distance of about two kilometres. The Bagnoli-Fuorigrotta Plain represents a inshore-offshore transition zone, whose geology is the result of a complex succession of volcano-tectonic and eustatic events, and sedimentary supply changes. To supplement the information obtained by the analysis of the wells and the seismic profiles is done use of the stratigraphic-sequential analysis. In fact, the sequential units are the alone ones that allow to conform the obtained interpretations to inshore, by the geological survey and the analysis of wells, with the interpretations obtained at offshore by the analysis of reflection seismic profiles. An integrated analysis of the data to inshore and offshore and a final correlation of the results has been executed. The study of the subsoil, using the well data, in the inshore coastal area of the Bagnoli-Fuorigrotta Plain, has produced the three-dimensional reconstruction of the facies and architectures of the deposits, to the recognition of the limits of sequences and the definition of their spatial distribution. The gotten reconstruction has allowed to individualize the faults, some still active, tied up to the principal volcano-tectonic events verified in this area, which has provoked the dismemberment of the plain in more sectors, causing relative movements of uplift and lowering. At offshore, despite the acquisition in analogical and not digital format of the geophysical data, the analysis of the seismic profiles has been effected, setting them with the next wells to the coastline, that has produced the recognition of the seismic facies and the reconstruction of the limits of sequence. The correlation of the limits of sequence individualized inshore and offshore is good. Particularly four principal sequences and three limits of sequence are been individualized, recognizable both to inshore and to offshore, and the principal active faults. This correlation allows a meaningful 4D reconstruction of the deposits of the subsoil in the coastal area of a geologically extremely complex zone.