Mount Etna as a Leaking Pipe of Magmas From the Low Velocity Zone

Abstract Mount Etna, one of the most active volcanoes on Earth, exhibits unusual characteristics in terms of its geological setting, effusion rate, and volatile content. Mount Etna is closely related to the subduction of the Ionian plate below Eurasia, but, chemically, Mount Etna lavas are akin to intraplate magmatism. Unlike typical oceanic islands such as Hawaii, Mount Etna eruptive sequence starts with small volumes of tholeiitic lava, then shifts to alkaline compositions with much higher effusion rates, raising questions about its magma sources and modes of generation. Here, we propose that the lavas erupted at Mount Etna originate from the extraction of pre‐existing melts stored within the Low Velocity Zone (LVZ). This zone characterizes the lithosphere–asthenosphere boundary (LAB) and is identified beneath oceanic plates by electric and seismic anomalies interpreted to reflect the presence of small melt fractions. We use geochemical data and modeling to show that extraction of such pre‐existing melts in the LVZ in response to plate flexure around Sicily and, when coupled with varying degrees of melt‐rock interaction, accounts for the temporal evolution of magma chemistry and eruptive volume at both Mount Etna and the earlier‐formed Hyblean Plateau. Our analysis suggests that extraction of low degree melts from the LVZ can give rise to large alkaline volcanoes in specific tectonic environments. Mount Etna may be a unique place on Earth where the compositions of melts at the LAB can be studied directly on the Earth's surface.