A long-lasting inflation at Mt. Etna volcano: revisiting the post 1991-1993 eruption time interval

Following the voluminous 1991-1993 eruption, Mount Etna experienced a period of low volcanic activity. A vigorous pressurization of the plumbing system of the volcano started in September 1993 as clearly documented by geodetic observations. This build-up phase ultimately culminated in the 2001 eruption. Leading up to this event, the volcano was highly restless, exhibiting frequent explosive activity at its central craters, summit lava flows, and notable seismic swarms on its western flank, particularly in January 1998 and April 2001. We revisited such vigorous pressurization by taking into account all available continuous and episodic GNSS observations collected during the 1994-2001 time interval. To this aim, we reprocessed all GNSS raw data by using the GAMIT/GLOBK code, aligning both time series and velocity field to a local reference frame, in order to remove the regional deformation pattern. We inverted the resulting surface velocity field to get new insight on the pressurizing source by adopting different analytical models. We framed achieved results in the general context of the eruptive cycles (inflation-eruption-deflation) characterizing Mt. Etna volcano in the last decades as well as providing also new insight on the long-term volcanic hazard assessment.