Multi-disciplinary reconstruction of magma dynamics during the 2020-22 paroxysmal sequence at Mt. Etna volcano

We present a multidisciplinary study combining volcanic tremor RMS amplitude and tilt deformation data analysis along with petrological and geochemical data collected for lava fountain activity between December 2020 and October 2021 at Mt. Etna. Geophysical data allowed the identification of 3 sub-periods of volcanic activity. During the first period, from February to April 2021, medium-high deformations and tremor values have been recorded, overall indicating significant volumes of volatile-rich magmas transferred from the deeper to the upper portions of the plumbing system. The second period, from May to June 2021, records the lowest deformation values of the entire eruptive sequence. These deformations are associated to a period of shorter durations of lava fountains and lower erupted volumes as a possible consequence of minor amounts of undegassed magmas in the uppermost feeding system, as also confirmed by SO2 emissions measured over the same period at the plume. During the third period, from July to October 2021, an increasing trend of the above cited parameters coupled with decreasing inflation velocity was detected. Compositional variations of the erupted tephra highlighted important changes in the evolution of magmas during the entire period of paroxysmal eruptions, also evidencing episodes of injection of more primitive magmas that are consistent with the observed patterns of deformation and volcanic tremor. The integration of geophysical and geochemical data has proved to be valuable in detecting the main magmatic processes and transfers dynamics that have produced the distinct features observed during the summit eruptions.