The 2020–2022 paroxysmal episodes of the South-East Crater (Mt. Etna): insights into high-frequency eruptive activity from petrological monitoring

Abstract Over the last 20 years, the South-East Crater (SEC) of Etna has produced high-intensity explosive activity including Strombolian explosions and lava fountains associated with lava effusion. In the 2020–2022 period, SEC volcanic activity was characterized by two paroxysmal sequences from 13 December 2020 to 1 Apr 2021 (SEQ1) and from 19 May to 23 October 2021 (SEQ2); another two paroxysms occurred on 10 and 21 February 2022. The 2020–2022 eruptive activity was monitored by the Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Etneo (INGV-OE) with instrumental networks, field surveys, and laboratory analyses. A detailed record of the chemical variations of glass was acquired in the framework of the syn-eruptive petrological monitoring; chemical (major and trace elements) and isotopic (Sr and Nd) compositions of bulk rocks completed the study. The findings of the petrological monitoring, coupled with volcanological parameters and literature data, allowed magma evolution to be tracked and the subsurface magmatic processes responsible for the observed compositional variations to be inferred. Changes in magma supply rates and mixing between an evolved magma stored in the shallow reservoir and a more primitive magma ascending from intermediate depths controlled magma evolution during the 2020–2022 paroxysmal activity. We discuss magmatic processes in the plumbing system before and during the eruption and the relationship between rate of magma supply and the eruptive dynamics. Finally, the 2020–2022 paroxysmal activity of SEC tested the INGV-OE procedures of petrological monitoring, in the framework of monitoring best practices.