Convective heat flux from hydrothermal system: First monitoring results at La Fossa of Vulcano

Abstract

Fluids circulating inside hydrothermal systems drive thermal and kinetic energy to balance the acting forces. Convective heat flux variations can be affected either by change in regional tectonic factor and by magma migration, both processes accountable for volcanic risk. The thermal release on quiescent volcano is not negligible if compared to that associated to eruptions, according to balances on hydrothermal activity and eruptive activity (Nuccio & Valenza, 1986, Chiodini et al., 2001). Moreover outlet temperature of La Fossa fumaroles (Vulcano, Aeolian Islands), indicates that thermal energy release is not stationary (Chiodini et al., 1992), showing relationships either with changes in the magmatic components of fluids and with seismic energy release (Badalamenti et al 1987, Nuccio et al 2000, Diliberto et al 2002). However at Vulcano, to estimate the time variation of convective heat flux, mainly steam output has been measured so far (Italiano & Nuccio ,1992; Italiano et al., 1998)…(b).. Indeed some interesting changes of heat flux from soil have been recorded, in 1998 and in 2004-2005, with anew method tested out of fumarole area. The first variation was related to the seismic crisis of November 1998 (Aubert & Alparone, 2000, Diliberto & Alparone, 2004); the second one (November 2004) was probably due to both magmatic fluids migration and little seismic activity. These results indicate that with this method future changes in the heat power (range or distribution) could be monitored to obtain new clues on the evolution of the activity.