Publication Date:
2020-06-30
Description:
Furnas volcano, in São Miguel island (Azores), being the surface expression of rising hydrothermal steam, is the site
of intense carbon dioxide (CO2) release by diffuse degassing and fumaroles. While the diffusive CO2 output has
long (since the early 1990s) been characterized by soil CO2 surveys, no information is presently available on the
fumarolic CO2 output. Here, we performed (in August 2014) a study in which soil CO2 degassing survey was
combined for the first time with the measurement of the fumarolic CO2 flux. The results were achieved by using a
GasFinder 2.0 tunable diode laser. Our measurements were performed in two degassing sites at Furnas volcano
(Furnas Lake and Furnas Village), with the aim of quantifying the total (fumarolic + soil diffuse) CO2 output. We
show that, within the main degassing (fumarolic) areas, the soil CO2 flux contribution (9.2 t day−1) represents a
minor (~15 %) fraction of the total CO2 output (59 t day−1), which is dominated by the fumaroles (~50 t day−1). The
same fumaroles contribute to ~0.25 t day−1 of H2S, based on a fumarole CO2/H2S ratio of 150 to 353 (measured
with a portable Multi-GAS). However, we also find that the soil CO2 contribution from a more distal wider
degassing structure dominates the total Furnas volcano CO2 budget, which we evaluate (summing up the CO2 flux
contributions for degassing soils, fumarolic emissions and springs) at ~1030 t day−1.
Description:
Published
Description:
4V. Dinamica dei processi pre-eruttivi
Description:
JCR Journal
Keywords:
Carbon dioxide flux
;
Soil diffuse degassing
;
Fumaroles
;
Furnas volcano
;
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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