GNGTS 2013 - Atti del 32° Convegno Nazionale

E-W elongated, culminating with the absolute magnetic minimum (-100 nT) in correspondence to the Baia Castle. Four magnetic sections have also been constructed (Aiello et al. , 2012). The first one runs from Punta Pennata (Gulf of Pozzuoli) to the Pozzuoli town (Via Napoli). The total magnetic intensity shows a trending with a magnetic minimum of – 80 nT in the central area (corresponding to a depth of the sea bottom of – 90 m) and a magnetic maximum of 70 nT in correspondence to the Pozzuoli shoreline. The section section runs from Bagnoli to Capo Miseno and shows, starting from south-west a monotonous magnetic trend up to the offshore surrounding Nisida, where a strong increase to the gradient occurs. The magnetic highs occurring nearshore appear to be related not to the geology, but to the occurrence of the industrial systems of Bagnoli. Conclusions. The Naples Bay is characterized by two main magnetic fields, offshore of Somma-Vesuvius and offshore the Phlegrean Fields volcanic complexes. Three magnetic maxima, dipolar in shape, are related to the Torre del Greco volcanic structure, already observed based on seismic interpretation (Aiello et al. , 2010). The rising of the Torre del Greco volcanic structure corresponds to the occurrence of topographic undulations of the sea bottom of up to ten metres. This is confirmed by the interpretation of seismic profiles, showing three main vertical culminations of the volcanic structure, linked to significant magnetic anomaly extremes. Significant anomalies have been identified offshore the Phlegrean Fields volcanic complex, in correspondence to the outer belt of the Gulf of Pozzuoli. They are related to volcanic bodies buried by sediments and to small volcanic edifices. Significant anomalies also occur in correspondence to the Magnaghi canyon, which is completely incised in volcanic deposits. The interpreted map of the magnetic anomalies in the Gulf of Pozzuoli has allowed to distinguish positive and negative magnetic anomaly areas. The inner continental shelf of the Gulf of Pozzuoli is characterized by negative magnetic anomalies and the correlation with the volcanic structures evidenced by the Sparker data is not clear. The volcaniclastic units identified on seismic profiles does not seem to produce significant magnetic signatures, probably due to its composition (tuffs and lavas). References Agip; (1981): Carta magnetica – Anomalie del campo magnetico residuo – scala 1:500.000. S. Donato Milanese, Italy. Aiello G., Angelino A., Marsella E., Ruggieri S. & Siniscalchi A.; (2004): Carta magnetica di alta risoluzione del Golfo di Napoli. Bollettino della Società Geologica Italiana, 123: pp. 333-342. Aiello G., Marsella E. & Ruggieri S. (2010): Three-dimensional magneto-seismic reconstruction of the “Torre del Greco” submerged volcanic structure (Naples Bay, Southern Tyrrhenian sea, Italy): Implications for the Vesuvius’ marine geophysics and volcanology. Near Surface Geophysics, 8 (1) : pp. 17-31. Aiello G., Cicchella A.G., Di Fiore V. &Marsella E.; (2011): New seismo-stratigraphic data of the Volturno Basin (northern Campania, Tyrrhenian margin, southetn Italy): implications for tectono-stratigraphy of the Campania and Latium sedimentary basins. Annals of Geophysics, 54 (3) : pp. 265-283. Aiello G., Giordano L., Marsella E. & Passaro S.; (2012): Seismic stratigraphy and marine magnetics of the Naples Bay (southern Tyrrhenian sea, Italy): the onset of new technologies in marine data acquisition, processing and interpretation. In: Elitok O. (Ed.) Stratigraphic Analysis of Layered Deposits. Intech Ed., Chapter 2; pp. 21-60. Bernabini M., Latmiral G., Mirabile L. & Segre A.G.; (1971): Alcune prospezioni sismiche per riflessione nei Golfi di Napoli e Pozzuoli. Rapp. Com. Inter. Mer. Medit., 21 : pp. 929-934. Caratori Tontini F., Faggioni O., Giori I. & Stefanelli P:, (2003): La nuova carta aeromagnetica d’Italia. Confronto con i principali lineamenti tettonico-strutturali. Atti 22° Cong. Naz. GNGTS, 3° Cong. Naz. EAGE-SEG, Rome (Italy), CNR, 19-21 November 2003. Cassano E. and La Torre P.; (1987): Geophysics. In: Santacroce R. (Ed.) Somma-Vesuvius. CNR, Quaderni De La Ricerca Scientifica, Rome, Italy. Castellano M., Buonocunto C., Capello M. & La Rocca M.; (2002): Seismic surveillance of active volcanoes: the Osservatorio Vesuviano seismic network (OVSN-Southern Italy). Seismology Research Letters, 73: pp. 177-184. Coticchia A., De Santis A., Di Ponzio A., Dominici G., Meloni A., Pierozzi M. & Sperti M.; (2001): La Rete Magnetica Italiana e la Carta Magnetica d’Italia al 20000. Boll. Geod. e Sc. Affini, Rivista dell’Istituto Geografico Militare, 4. Finetti I. and Morelli C.; (1973): Esplorazione sismica per riflessione dei Golfi di Napoli e Pozzuoli. Boll. Geof. Teor. Appl., 16 (62-63) , pp. 175-222. Galdi A., Giordano F., Sposito A. & Voltaggio M.; (1988) Misure geomagnetiche nel Golfo di Pozzuoli: Metodologia e risultati. Atti del 7° Convegno GNGTS-CNR, 3 : pp. 1647-1658. 90 GNGTS 2013 S essione 3.2