Recent magma supply dynamic at Mt Etna volcano inferred from periodic measurements of soil CO2 emissions

Periodic surveys for the measurement of the soil CO₂ flux are regularly performed in three peripheral areas of the Mt Etna (Paternò, Zafferana-S. Venerina and Vena-Presa) for a whole of 140 measurement sites. It is widely demonstrated that anomalous emissions of CO₂ in these areas are linked to magma supply dynamics. Herein we report the data of soil CO₂ flux periodically recorded in these areas from 2015 to 2022. We processed and analyzed the data to reconstruct the magma supply dynamics over the considered period and showed as variations are related to the most significant eruptive phases which occurred through the investigated period.

One of the hallmarks eruptive episode occurred on 24th December 2018, from an eruptive fissure which opened on the New Southeast Crater (NCSE) flank. During this event both ash-rich plumes from the summit craters and intense strombolian activity along the fissure were observed. This episode was associated with intense seismic swarms. Mild strombolian activity, ash emission at summit craters, and constant inflation of the volcano edifice during autumn 2018 preceded the eruptive episode. The soil CO₂ flux measured in the more distal peripheral areas reveal that, at least three episodes of magmatic supply into the deep system (7-13 km b.s.l.) occur in the Etna feeding system, since 2016. After November 2018, a remarkable increase in the soil CO₂ emissions was recorded at Vena-Presa area, along the Pernicana fault, suggesting magma transfer into the shallower portions of the feeding system. The volcanic origin of this degassing event was confirmed also by isotopic signature of carbon of CO₂.

Another notably eruptive phase occurred on 2021 at the NSEC, with a sequence of seventeen lava fountains from 16 February to 1 April 2021. Some of these events were the most intense among those which occurred at Mt. Etna in the last ten years. A few months earlier (July-December 2020) we detected a huge increase of CO₂ emissions in the Paternò area, with the highest value ever recorded over the last 15 years.