La piana campana: un monumento geologico di 5.000 km2 dal tirreno all’appennino

Bologna

Abstract – The Campanian Plain: a geological monument of 5.000 km2 from the
Tyrrhenian Sea to the Apennines - The Campanian Plain is the region in Southern Italy which extends between the Apennine Chain and Tyrrhenian Sea over an area of 5,000 km2 from Mt. Massico, in the north, to Sorrento Peninsula in the south of the Plain. The ancient name of this area was Campania Felix. This territory is an extraordinary geological monument characterized by
volcanoes, earthquakes, tsunamis, slow ground vertical movements (bradiseism) which
generated myths, legends, archeological findings, historical documents. The Campanian Plain is affected by extensional tectonics related to the spreading of the Tyrrhenian Basin. The onset of this process occurred between the Mid–Pliocene and the Early Pleistocene, when large morpho-structural depressions began to develop, giving rise to the Bay of Naples. The whole range of phenomena observed, in particular the recent tectonics and chemism of magmas feeding active volcanoes can be accounted for the local upwelling of the Mantle, the lytosphere plate bending and subsequent collapses.
The measure of the collapse in the Campanian Plain, due to the stretching of the crust
produced by the Mantle migration, is obtained by the thickness of sediments forming
Campanian Plain. These data and the time lapse of the process furnish a value of about 1-2 mm/yr for the velocity of the subsidence during the Quaternary. Coeval to the
deformation of this morphostructural depression was the onset of intense magmatic
activity with the formation of the polygenic apparatus of Mt. Vesuvius and the volcanic
fields of Phlegraean Fields and Ischia Island. In the Phlegrean Fields and Ischia caldera
collapses, ignimbrite eruptions, and caldera resurgences occurred; instead at Vesuvius
numerous Plinian eruptions were recorded. The most recent eruptions in the Neapolitan area occurred in 1302 at Ischia, 1538 at Phlegrean Fields and 1944 at Vesuvius. At present large fumarolic fields and thermal springs outcrop in several sites, while in the Phlegrean Fields slow oscillations of ground are recorded.
The eruptive history of neapolitan volcanoes, the seismic history of Southern
Appennines as well as the geological features of Campanian Plain characterize this
area as a geological multirisk territory. Thus it is a “laboratory” for volcanic, seismic and
hidrogeological risk assessment, from wich to draw lessons for integrated planning of
pleasant places in risk areas.