Large dyke intrusion and small eruption: The December 24, 2018 Mt. Etna eruption imaged by Sentinel-1 data

On December 24th, Mt. Etna volcano underwent a seismic crisis beneath the summit and upper southern flank of the volcano, accompanied by significant ash emission. Eruptive fissures opened at the base of summit craters, propagating SE-wards. This lateral eruption lasted until December 27th. Despite the small eruption, seismic swarm and ground deformation were very strong. Sentinel-1 interferograms show a wide and intense ground deformation with some additional features related to volcano-tectonic structures. We inverted DInSAR data to characterise the magma intrusion. The resulting model indicates that a large dyke intruded but aborted its upraise at about the sea level; however, this big intrusion stretched the edifice, promoting the opening of the eruptive fissures fed by a shallower small dyke, and activating also several faults. This model highlights that a big intrusion beneath a structurally complex volcano represents a main issue even if the eruption is aborted.