Summit activity at Mt. Etna, Sicily, Italy: long-period (2010-2024) petrologic study to investigate the high-energetic paroxysmal activity

Mt. Etna, the most active volcano of Europe, produces both summit and flank eruptions. In recent decades, the summit eruptions have been more common than flank ones. They occur from the four summit craters, namely the South-East Crater, the youngest and the most active, the North-East Crater, the Voragine Crater and the Bocca Nuova Crater. Summit eruptions can also be generated by branching of the central conduits opened in sub-terminal position, i.e. slightly downslope from the summit craters. Besides the location of the eruptive vents, summit eruptions show a range of eruptive style, from discrete Strombolian explosions to high-intensity paroxysmal events characterized by lava fountains producing high-altitude ash plumes, and associated with lava effusion.

Here, we study a period of summit activity that began after the end of the long-lasting 2008-2009 eruption. More precisely, we investigate from 2010 to 2024, focusing on distinctive paroxysmal sequences, which mostly involved the South-East Crater (SEC) and, to a lesser extent, the Voragine Crater (VOR). Overall, The SEC produced 25 episodes in 2011–2012 and 23 in 2013–2014, while 4 and 2 episodes occurred at the VOR in December 2015 and May 2016, respectively. In recent years, more than 60 episodes took place at the SEC in December 2020-February 2022, and 7 at the VOR in July and November 2024. Noteworthy, the characteristics of paroxysmal activity at the two summit craters differ significantly for the number of events, the duration of each sequence, the repose period between episodes, the total volume of the erupted products, the proportion of tephra and lavas, the impact of the eruptive activity on the morphology of the summit area, as well as the texture and composition of the erupted products.

Although several petrological studies have considerably improved the knowledge of Etna’s summit explosive activity in the last decades, long-term investigations focused on paroxysms are scarce. Therefore, in the framework of petrological monitoring of the Etna Observatory, we carried out a regular sampling of the products erupted from 2010 to 2024, which have been analysed for petrographic textures and the compositions of glass, major and trace elements, as well as Sr-Nd isotopes. The research is still in progress.

The expected results will help to: i) deepen the knowledge of the magmatic processes (mafic recharge, magma mixing and crystallization), ii) investigate if/how pre-eruptive magma dynamics influence the syn-eruptive processes driving paroxysmal activity at SEC and VOR, iii) gain insight into the role that tectonic and /or geometry of the shallow plumbing system can play in determining different characteristics of paroxysmal activity at the SEC and the VOR, and finally iv) explore if the products erupted before a paroxysmal sequence show textural and compositional features heralding the onset of  paroxysms.

The scientific community has the important goal of deeply understanding the magmatic processes and mechanisms at the root of the paroxysmal activity in order to provide crucial information to the authorities in charge of mitigating hazard associated with such activity.