Abstract : Mount Etna volcano is well-known for its frequent eruptions
and high degassing rates from its summit craters and flanks. The
geochemical monitoring network on Mt. Etna that measures soil CO2
flux and in-plume CO2/SO2 ratio recorded very important degassing
variations from the flank and the summit craters during the second
half of 2018. In this area several significant volcanic events occurred in
October and December 2018 and in January 2019. Past observations
have distinguished a tendency for wide variations in degassing rates,
marked by a sharp increase preceding the onset of volcanic activity.
However, this is the first time that three earthquakes of magnitude
M>4 have been registered since the inception of the geochemical
network in January 2001. Of particular interest is the CO2/SO2 ratio in
plumes recorded by the monitoring station sited at the summit crater
of Voragine showed very significant degassing variations, which were
comparable with those recorded for the soil CO2 flux.
This paper focuses on the combination of events occurring
on Mt. Etna and their relationship with degassing rates. The most
remarkable results can be summarized as follow: i) the networks
recorded high variations of soil CO2 flux and CO2/SO2 ratio, which
assisted in identifying distinctive phases of pressurization of Mt. Etna
plumbing system and ii) all earthquakes occurred during phases of
minimum gas rate, which in turn followed stages of pressurization
involving different portions of the plumbing system. The 2018 period
of high volcanic activity and the corresponding seismic episodes
provided an invaluable case study for Mt. Etna, which allowed to
combine seismic events and geochemical signal variations.
