Surface heat flow density at the phlegrean fields caldera (SOUTHERN ITALY)

Abstract The Phlegrean Fields area is a Holocene caldera located west of Naples, southern Italy. The recent post-caldera activity is characterized by several eruptive centers inside the collapsed area. In order to investigate the still active volcanic processes, surface heat flow measurements were carried out in 1995 in 30 sites of the Phlegrean Fields, and a heat flow map compiled. Filtering of the map reveals some well-defined anomalies superimposed on a general southward-increasing trend. Local anomalies are related to small magma bodies, whereas the observed general trend has been attributed to the effect of groundwater flow. This effect was calculated and removed. The undisturbed mean value of the surface heat flow density in the eastern sector is 149 mW\m 2 , which is above the regional value of 85 mW\m 2 assigned to the eastern part of the Tyrrhenian Sea, and which is probably influenced by a very large, deep magmatic body.