Internal structures of the Campi Flegrei caldera by gravimetric data

A model of the crustal structures in the Campi Flegrei caldera has been developed from gravimetric data collected along a profile crossing the central zone of the caldera. The model includes a low-density body (2300 kg/ m3 in its inner core and 2400 kg/m3 in the outer), intruded into thermally metamorphosed basement (with a density of 2600 kg/m3); the top of this low-density body is at a depth of about 3 km. Sediments ranging from 1800 to 2200 kg/m3, which characterize the caldera fill, lie on the metamorphosed basement; the contact between the two lies at a depth of about 2.5 km. The model fits the gravity minimum found in the caldera and is in good agreement both with the volcanic history of the area and recent dynamic processes.