Modeling the dynamics of lava fountains at Etna

In recent years, Etna's primary eruptive activity has been marked by extended sequences of lava fountain episodes. Lava fountains are explosive events involving intense jets of gas and solid particles, which significantly impact air traffic and urban areas due to ash dispersal and fallout. The development of a lava fountain at Etna typically follows a gradual progression: it begins with weak Strombolian activity, transitions to a characteristic lava jet, and culminates in the formation of a sustained eruptive column. These events generally last from several minutes to a few hours. During such eruptions, the interaction between magma and surrounding rock induces very small deformations that can be detected by a Sacks-Evertson strainmeter. This instrument measures the volumetric deformation of the surrounding rock with high resolution and across a broad frequency range. Analyzing strain data helps determine the timing of events, assess the fountain's magnitude, and estimate the volume of material erupted.

In this study, we propose a time-dependent model of shallow reservoir withdrawal, incorporating fluid dynamics within the conduit and associated pressure variations. The resulting variations of the strain field in the surrounding rocks is compared with data collected at Etna during lava fountaining episodes.