Publication Date:
2019-02-07
Description:
Mount Etna volcano (Sicily, Italy) is the place where short-lived radioactive disequilibrium
measurements in volcanic gases were initiated more than 40 years ago. Almost two decades after the
last measurements in Mount Etna plume, we carried out in 2015 a new survey of 210Pb-210Bi-210Po
radioactive disequilibria in gaseous emanations from the volcano. These new results [(210Po/210Pb) =
42 and (210Bi/210Pb) = 7.5] are in fair agreement with those previously reported. Previously
published degassing models fail to explain satisfactorily measured activity ratios. We present here
a new degassing model, which accounts for 222Rn enrichment in volcanic gases and its subsequent
decay into 210Pb within gas bubbles en route to the surface. Theoretical short-lived radioactive
disequilibria in volcanic gases predicted by this new model differ from those produced by the former
models and better match the values we measured in the plume during the 2015 campaign. A Monte
Carlo-like simulation based on variable parameters characterising the degassing process (magma
residence time in the degassing reservoir, gas transfer time, Rn-Pb-Bi-Po volatilities, magma volatile
content) suggests that short-lived disequilibria in volcanic gases may be of use to infer both magma
dynamics and degassing kinetics beneath Mount Etna, and in general at basaltic volcanoes. However,
this simulation emphasizes the need for accurately determined input parameters in order to produce
unambiguous results, allowing sharp characterisation of degassing processes.
Description:
Published
Description:
Article 27
Description:
3V. Proprietà dei magmi e dei prodotti vulcanici
Description:
JCR Journal
Keywords:
adioactive disequilibria 210Pb-210Bi-210Po; volcanic gases; degassing processes; geochemical modelling;Mount Etna
;
04.08. Volcanology
;
gas
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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