GNSS-based long-term deformation at Mount Etna volcano (Italy)

We estimated a long-term velocity field for Mount Etna volcano by taking into account a dense GNSS dataset collected during the 2004.42 - 2018.95 period. To properly isolate the volcanic deformation from the background tectonic one, we defined a new local reference frame (termed MERF23) by using 32 stations mainly located in north-western and south-eastern Sicily. The computed long-term velocity field well highlights contrasting patterns between the north-western flank and the eastern one. The north-western flank was characterized by a general radial pattern with small deformations, mainly related to inflation and deflation episodes occurred during the investigated period. The eastern flank was characterized by a vigorous seaward motion, with rates ranging from ∼60 mm/yr on the Pernicana fault (northern boundary) to ∼29 mm/yr along the Aci Trezza fault (southern boundary), clearly evidencing as flank instability remains by far the predominant type of deformation at Mount Etna. A small contraction along the peripheral base of the volcano, coupled with a small uplift has been also detected; both patterns lend credit to the concurrent action of different processes as local and regional tectonics as well as long-term magmatic doming.