Publication Date:
2017-04-04
Description:
La Fossa quiescent volcano and its surrounding area on the Island of Vulcano (Italy) are
characterized by intensive, persistent degassing through both fumaroles and diffuse soil emissions. Periodic
degassing crises occur, with marked increase in temperature and steam and gas output (mostly CO2) from
crater fumaroles and in CO2 soil diffuse emission from the crater area as well as from the volcano flanks and
base. The gas hazard of the most inhabited part of the island, Vulcano Porto, was investigated by simulating
the CO2 dispersion in the atmosphere under different wind conditions. The DISGAS (DISpersion of GAS) code,
an Eulerian model based on advection-diffusion equations, was used together with the mass-consistent
Diagnostic Wind Model. Numerical simulations were validated by measurements of air CO2 concentration
inside the village and along the crater’s rim by means of a Soil CO2 Automatic Station and a Tunable Diode
Laser device. The results show that in the village of Vulcano Porto, the CO2 air concentration is mostly due
to local soil degassing, while the contribution from the crater gas emission is negligible at the breathing
height for humans and always remains well below the lowest indoor CO2 concentration threshold recommended
by the health authorities (1000 ppm). Outdoor excess CO2 maxima up to 200 ppm above local background
CO2 air concentration are estimated in the center of the village and up to 100 ppm in other zones. However, in
some ground excavations or in basements the health code threshold can be exceeded. In the crater area,
because of the combined effect of fumaroles and diffuse soil emissions, CO2 air concentrations can reach
5000–7000 ppm in low-wind conditions and pose a health hazard for visitors.
Description:
Published
Description:
5398–5413
Description:
4V. Vulcani e ambiente
Description:
JCR Journal
Description:
reserved
Keywords:
Volcanogenic carbon dioxide plume
;
Air CO2 concentration
;
04. Solid Earth::04.08. Volcanology::04.08.01. Gases
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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