Diffuse emission of CO 2 from the Fossa crater, Vulcano Island (Italy)

Abstract

Numerous measurements of CO 2 degassing from the soil, carried out with the accumulation chamber method, indicate that in the period April-July 1995 the upper part of the Fossa cone released a total output of 200 t d -1 of CO 2 , which corresponds to approximately 1000 t d -1 of steam. These large amounts of fluids are of the same order of magnitude as those released by the high temperature fumarolic field located inside the crater. The spatial distribution of soil gas fluxes shows that the main structures releasing CO 2 are the inner slopes of the crater and a NW-SE line, located NE of the crater rim, which correspond to the main direction of Vulcano Island active faults. The comparison of the wCO 2 maps with the soil temperature distribution, derived from both direct measurements and airborne infrared images, indicates the occurrence of extensive condensation of fumarolic steam within the upper part of the Fossa cone, whose total amount is comparable to the rainfall budget. Part of the condensate which originates from this process contributes to the recharge of the phreatic aquifer of Porto Plain, modifying the chemical and isotopic composition of the groundwater.

UV camera measurements of fumarole field degassing (La Fossa crater, Vulcano Island)

“…5). Our mean CO 2 flux of~490 t d −1 (average of the two surveys) is between 2 and 6 times larger than that of the CO 2 flux diffusely degassed from soils in the Vulcano Porto area (Chiodini et al, 1996), highlighting that the central conduit system feeding the fumaroles is the main gas transfer path. We also evaluate a mean H 2 O flux of~400 t d −1 , close to earlier estimates by Italiano et al (1998) and Chiodini et al (2005).…”

Diffuse emission of carbon dioxide from Cerro Negro Volcano, Nicaragua, Central America

“…This relation also suggests that most of the soil degassing at Cerro Negro is generated by shallow steam condensation. A similar process is described for Vulcano, Italy (Chiodini et al, 1996). Advective processes generated by gas pressure build-up at depth may be playing an important role on the degassing mechanism and appearance of soil anomalies in the proximity of deep reaching faults/fractures and areas with high vertical permeability.…”

Geochemical Assessment for Morendat East Geothermal Prospect, Using Radon and Carbondioxide Concentration from Soil, Kenya

“…CO 2 soil gas investigation procedure is similar to the one used in this study has been conducted in various volcanic areas to examine the mechanism of CO 2 flux [16][17][18]. The same procedure has also been applied in the estimation of total volcanic flux from volcanic vents and diffuse flank emissions [19,20], and to classify tectonic structures related to volcanic degassing [21,22].…”