GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.3 195 was gradually upgraded over the years in order to cover all the slopes of the volcano edifice and to replace the sites destroyed by natural (lava flows) and human (vandalism) activities, reaching the current configuration of 33 stations (Fig. 1). All raw GPS observations, collected since January 2001, were processed by using the GAMIT/GLOBK software and by taking into account precise ephemerides from the “International GNSS Service” and Earth orientation parameters from the “International Earth Rotation Service”. Estimated GPS daily time series has been referred to a local reference frame (hereinafter MERF18) in order to isolate the Mt. Etna volcanic deformation from the background tectonic pattern. By inspecting the daily baseline changes for EDAM and EMGL stations (Fig. 2) we detected 51 different ground deformation stages, capturing well 19 deflationary, 24 inflationary episodes, as well as the occurrence of 4 magmatic dike intrusions and 4 periods of no deformation. For each detected stage we estimated the ground deformation field in terms of geodetic velocities by combining the daily GAMIT solutions into a consistent set of station positions and velocities, referred to MERF18. Fig. 2 - EDAM - EMGL baseline time series. The surface deformation for each deformation stage was used to constrain isotropic half- space elastic inversion models by using a genetic algorithms approach (Tiampo et al. , 2000) and adopting the analytical spheroidal pressure source described in Yang et al. (1988). Petrological and geochemical data. Major and trace element concentrations together with radiogenic isotope compositions for the volcanic products erupted throughout the 2001-2018 period put into evidence very complex variations at variable time scales, i.e. during the whole considered time span but even at the scale of the single eruption (e.g., 2001 eruption, 2006 eruption; Viccaro et al. , 2006; 2015; 2016; 2019; Ferlito et al. , 2012; Nicotra and Viccaro, 2012; Giuffrida and Viccaro, 2017; Cannata et al. , 2018). These variations should be attributed to a general trend of magma evolution occurring into the volcano plumbing system coupled with various episodes of recharge and interaction between compositionally distinct magma batches. Petrological and geochemical data suggest that hybridization involved either magmas differing profoundly in their geochemical signature (a trend more evident in the 2001-2006 volcanic products) or only in terms of evolutionary degree (a trend more evident in volcanic rocks erupted after 2011). Textural and compositional variations especially of plagioclase and olivine crystals refine our spatial reconstruction, also defining the thermodynamic conditions that magmas experienced during their run-up to the surface (Viccaro et al. , 2016; 2019; Nicotra and Viccaro, 2012; Kahl et al. , 2015; Giuffrida and Viccaro, 2017; Cannata et al. , 2018). Discussion and conclusions. Inversion of surface deformation patterns allowed the identification of main pressurizing/depressurizing magmatic sources active during the last