Steam output from fumaroles of an active volcano: Tectonic and magmatic-hydrothermal controls on the degassing system at Vulcano (Aeolian arc)

Abstract

The rcsults from measurements of extensive parameters (steam output and exhaling surface area) taken at the crater fumarolic field of Vulcano Island (Aeolian arc, southern Italy)are repoded along with a detailed description of the measuring method. The stem emission rate increased by 1 order of magnitude during the observation time (1983-19951, wlde its concenkation in the released gases was only slightly changed. During the same period the total exhaling surface expanded from 50 m2 to more than 2400 m2 and evolved following preferential trends that coincide with the maul tectonic structures of the island. The observed peaks in steam output slow a positive correlation with episodes of volcanic activity unrest. The temporal increase of steam output and the observed development in the exhaling surface areas are consistent with a volcaxo-tectonic triggering or the exhalating tivity. Particularly, the peaks in the steam outpuat re interpreted as a consequence of degassing from an active magma, slowly moving toward the surface.