Publication Date:
2017-04-04
Description:
We applied the Multi-GAS technique to measure compositions of the volcanic plumes
continuously discharged from summit craters of Voragine, Northeast and Bocca Nuova at
Mount Etna, in an attempt to estimate compositions of the source volcanic gases. The
estimated CO2/SO2 and H2O/CO2 ratios of the volcanic gases show a large variation
ranging from 0.6 to 30 and from 1 to 18, respectively. This variability overlaps with the
compositional range of dissolved volatiles in melt inclusions and their coexisting bubbles in
a magma chamber and can be caused by the low-pressure degassing of a magma with
variable bubble content ranging from 0.3 to 15 wt.%. The variable bubble content in the
magma is likely a result of supply of deep-derived CO2-rich gas phase to the chamber and
subsequent bubble-magma differentiation by bubble ascent in the magma chamber. In
contrast, the variation of volcanic gas composition can also be caused by changes of
degassing pressure (gas–magma separation pressure), ranging from 0 to 100 MPa, as a
result of changes in the depth of the top of the convecting magma in volcanic conduits. Both
mechanisms can cause similar compositional variations. However, the two mechanisms
will result in contrasting correlations between the SO2 emission rates and the gas
compositions that can be examined by parallel observations of the emission rates and
compositions in the future.
Description:
Published
Description:
B09203
Description:
1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
Description:
4.5. Degassamento naturale
Description:
JCR Journal
Description:
reserved
Keywords:
Plume
;
gas
;
04. Solid Earth::04.08. Volcanology::04.08.01. Gases
;
04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
