The 3rd July 2019 paroxysm at Stromboli: insights into volcanic ballistics dispersion

Abstract

Abstract High resolution dispersion of the ballistic projectiles erupted at Stromboli (Aeolian Archipelago, Italy) during the early phase of the 3rd July 2019 paroxysm was digitally reproduced and analysed. The paroxysms punctuate the persistent mild-explosive activity of Stromboli producing fallout of ballistic juvenile and lithic bombs that represent a serious threat for tourists climbing the volcano and for people living in the island. Drone images, acquired within a few days after the first 2019 paroxysm, were elaborated on GIS environment to identify and reproduce, as geo-spatial features, the ballistic spatter clasts emplaced on the volcano. The results indicate that 152,228 scattered spatter clasts, whose dimensions range from 0.03 m2 (16 cm x 16 cm) to 4.23 m2 (~ 2 x 2 m), were emitted on the east flank during the paroxysm. Such spatters represent the scattered clasts dispersed on 0.407 km2, and cover a total area of 29,000 m2 corresponding to an erupted products volume of 6–7*103 m3, calculated here for the first time. Further spatial and fitting analyses on spatter clasts distribution reveal the main dispersion trends of the ballistics, highlighting as the terrain morphology can influence the dynamic of the clasts emplacement.