Eruption dynamics of the 23 February 2013 event at Mt. Etna

Volcanic activity at Mt. Etna in the last decade has mostly been manifested by sequences of short paroxysmal episodes characterised by powerful lava fountains and high eruption columns. On the 23 February 2013, an exceptionally intense episode occurred at the New South-East Crater, producing a fountain > 800 m high (among the highest ever recorded at Etna) and a ∼9 km eruption column that dispersed ash > 400 km from the vent. Textural and petrographic analyses of lapilli revealed that magma erupted during the high-intensity phase is characterised by low microlite contents (< 7 area%), high vesicularity (76–83%), and high vesicle number densities (6–8.2 × 10⁶ cm^-3). The short-lived initial Strombolian explosions removed viscous magma from the conduit, enabling the rapid ascent of gas-rich, microlite-poor magma and the eruption of an 800 m high fountain and 9 km high eruption column. For the 23 February eruption, the high vesicularity and low microlite content of the pyroclasts support the hypothesis that volatile-rich magma was the driver of the high intensity lava fountain. This eruptive event, along with three other recent events at Etna over the last 15 years, can be defined as subplinian based on eruption rate and column height, but also generated incandescent 800–1000 m fountains. For these reasons, we propose to term this event, and others at Etna characterised by similar eruption features and parameters, as subplinian fountaining events.