The eruptions of December 2015 and May 2016 at Voragine crater were among the most explosive recorded during the last two decades at Mt. Etna volcano. Here we present data coming from geophysics (infrasound, LP, VLP, volcanic tremor, VT earthquakes, and ground deformations) and petrology (textural and microanalytical data on plagioclase and olivine crystals) to investigate the preeruptive magma storage and transfer dynamics leading to these exceptional explosive eruptions. Integration of all the available data has led us to constrain chemically, physically, and kinetically the environments where magmas were stored before the eruption, and how they have interacted during the transfer en‐route to the surface. Although the evolution and behavior of volcanic phenomena at the surface was rather similar, some differences in storage and transfer dynamics were observed for 2015 and 2016 eruptions. Specifically, the 2015 eruptions have been fed by magmas stored at shallow levels that were pushed upward as a response of magma injections from deeper environments, whereas evidence of chemical interaction between shallow and deep magmatic environments becomes more prominent during the 2016 eruptions. Main findings evidence the activation of magmatic environments deeper than those generally observed for other recent Etnean eruptions, with involvement of deep basic magmas that were brought to shallow crustal levels in very short time scales (∼1 month). The fast transfer from the deepest levels of the plumbing system of basic, undegassed magmas might be viewed as the crucial triggering factor leading to development of exceptionally violent volcanic phenomena even with only basic magma involved.

On 24 December 2018, a violent eruption started at Mount Etna from a fissure on the southeastern flank. The intrusive phenomenon, accompanied by intense Strombolian and lava fountain activity, an ash‐rich plume, and lava flows, was marked by significant ground deformation and seismicity. In this work, we show how an integrated investigation combining high‐rate GPS data, volcano‐tectonic earthquakes, volcanic tremor, infrasound tremor, and infrasound events allows tracking the magma intrusion phenomenon spatially and temporally with unprecedented resolution. Moreover, it enabled showing how the central magma column lowered as a response to the flank eruption and to constrain the zone of interaction between the dike and the central plumbing system at a depth of 2–4 km below sea level. This is important for understanding flank and summit interaction, suggesting that explosive summit activity may in some cases be driven by lateral dike intrusions.

13Here we report the first measurements of gas masses released during a rare period of 14 strombolian activity at the Bocca Nuova crater, Mt. Etna, Sicily. UV camera data acquired for 15 195 events over a ≈ 27 minute period (27th July 2012) indicate erupted SO 2 masses ranging 16 from ≈ 0.1 to ≈ 14 kg per event, with corresponding total gas masses of ≈ 0.1 to 74 kg. Thus, 17 the activity was characterised by more frequent and smaller events than typically associated 18 with strombolian activity on volcanoes such as Stromboli. Events releasing larger measured 19 gas masses were followed by relatively long repose periods before the following burst, a 20 feature not previously reported on from gas measurement data. If we assume that gas 21 transport within the magma can be represented by a train of rising gas pockets or slugs, then

Between January 2011 and April 2013, Mt. Etna's eruptive activity consisted of episodic intracrater strombolian explosions and paroxysms from Bocca Nuova, Voragine, and the New South‐East (NSEC) summit craters, respectively. Eruptions from NSEC consisted of initial increasing strombolian activity and lava flow output, passing to short‐lasting lava fountaining. In this study we present seismic, infrasound, radiometric, plume SO2 and HCl fluxes and geodetic data collected by the INGV monitoring system between May 2012 and April 2013. The multiparametric approach enabled characterization of NSEC eruptive activity at both daily and monthly time scales and tracking of magma movement within Mt. Etna's plumbing system. While seismic, infrasound and radiometric signals give insight on the energy and features of the 13 paroxysms fed by NSEC, SO2 and halogen fluxes shed light on the likely mechanisms triggering the eruptive phenomena. GPS data provided clear evidence of pressurization of Mt. Etna's plumbing system from May 2012 to middle February 2013 and depressurization during the February–April 2013 eruptive activity. Taking into account geochemical data, we propose that the paroxysms' sequence represented the climax of a waxing‐waning phase of degassing that had started as early as December 2012, and eventually ended in April 2013. Integration of the multidisciplinary observations suggests that the February–April 2013 eruptive activity reflects a phase of release of a volatile‐rich batch of magma that had been stored in the shallow volcano plumbing system at least 4 months before, and with the majority of gas released between February and March 2013.

We report on a systematic record of SO 2 flux emissions from individual vents of Etna volcano (Sicily), which we obtained using a permanent UV camera network. Observations were carried out in summer 2014, a period encompassing two eruptive episodes of the New South East Crater (NSEC) and a fissure‐fed eruption in the upper Valle del Bove. We demonstrate that our vent‐resolved SO 2 flux time series allow capturing shifts in activity from one vent to another and contribute to our understanding of Etna's shallow plumbing system structure. We find that the fissure eruption contributed ~50,000 t of SO 2 or ~30% of the SO 2 emitted by the volcano during the 5 July to 10 August eruptive interval. Activity from this eruptive vent gradually vanished on 10 August, marking a switch of degassing toward the NSEC. Onset of degassing at the NSEC was a precursory to explosive paroxysmal activity on 11–15 August.