The seismicity of the Mt. Etna in the period January - December 2020

This work describes the main characteristics of the seismicity due to the volcano-tectonic events recorded at Mount Etna during 2020. The data are recorded by the seismic stations of the Permanent Seismic Network operated by National Institute of Geophysics and Volcanology - Etna Observatory (INGV -OE). In this year, about 100 seismic stations constitute the network. The seismic data are first transmitted in real time to the Unified Data Acquisition Centre (CUAD) and then continuously transferred and recorded in the Control Room of INGV - OE. The Analyst Working Group of the Etna Observatory (GLAOE) reviews and reprocesses the seismic data the day after they are acquired, observing standard protocols which are adopted for the compilation of the catalogues and the databases relative to the volcanic areas pertaining to the observatory. The data analyses are performed every day by the GLAOE, and are among the monitoring activities provided by the INGV in the framework of the Accordo Quadro INGV - Civil Protection Department (DPC) 2012-2021 (Allegato A). During 2020, 3604 earthquakes were recorded in the Etna area, and of these, 2287 were localised. The focal depth is between-1.6 km a.s.l. and 35 km b.s.l., while the local magnitude (ML) is from 0.2 to 3.7. The magnitude of completeness (MC) of the 2020 resulting catalogue is equal to 1.2 (+/- 0.01), a value comparable to that calculated for 2017 and 2019, but 0.1 units higher than that estimated for 2018. The seismic events with ML > 3.0 are 15 and above all belonging to one of the 11 seismic sequences identified for 2020. The seismic sequence occurred on December the 31st and started at the 19:59 (UTC) is the most important one, since includes the highest number of events (21) and the most energetic earthquake of the year (ML = 3.7).