SEISMIC STUDY OF THE MESOZOIC CARBONATE BASEMENT AROUND MT. SOMMA-VESUVIUS, ITALY

Fifteen seismic reflection lines from AGIP surveys, in and around the Campanian Plain and Mt. Somma-Vesuvius (south Italy) have been interpr eted. The attention has been focused to the horizon pertinent to the t op of the Mesozoic carbonate sequence and the Quaternary faults dissec ting it. As a matter of fact, both are very important elements for und erstanding the origin of the volcanic activity in the area, that often in the past, has been the topic of debates not supported by reliable data. In the study area, referring to the depth of the carbonate basem ent, comparison between the result achieved by the seismic prospecting and previous gravity studies has been made. It shows coherence in som e areas but large discrepancy within others. Near the town of S. Anast asia, the gravity and seismic depth estimates differ as much as 1000 m or more. Furthermore, the seismic data show that the source of the gr eatest volcanic eruption in the area (the so-called 'Campanian Ignimbr ite') is probably not located in the Acerra depression, as suggested b y other authors. A main NE-SW fault directed toward Vesuvius, consider ed as playing a primary role on volcanogenetic processes and previousl y recognised only offshore by marine seismic survey, has been now iden tified also inland using this new seismic information. The results pre sented here strengthen the hypothesis that Mt. Vesuvius is located at the crossing point of two regional Quaternary sets of fault heading NW -SE and NE-SW. (C) 1998 Elsevier Science B.V. All rights reserved.