GRAVITY CHANGES INDUCED BY HEIGHT MASS VARIATIONS AT THE CAMPI-FLEGREI CALDERA

The Campi Flegrei caldera, located west of Naples (southern Italy), was subjected to significant gravity changes during the last bradiseismic crisis, starting in 1982. Since the beginning of the crisis, variations in the gravity field were accompanied by ground movements and seismicity. A detailed analysis carried out on the gravity changes, after removing the effect of the elevation changes, suggests that during the uplift phase a magma injection occurred in the central part of the caldera, at the eastern edge of the source 3 km deep. During deflation, the gravity variations may be due to magma drainage. Removal of fluid from a deep hydrothermal system may also be indicated. The gravity data also indicate the end of the 1982 crisis.