Intense overpressurization at basaltic open-conduit volcanoes as inferred by geochemical signals: The case of the Mt. Etna December 2018 eruption
Antonio Paonita, Marco Liuzzo, Giuseppe Salerno, Cinzia Federico, Pietro Bonfanti, Antonio Caracausi, Giovanni Giuffrida, Alessandro La Spina, Tommaso Caltabiano, Sergio Gurrieri, Gaetano Giudice
Abstract
The balance between the amount of gas coexisting with mantle-derived magmas at depth and that emitted during intereruptive phases may play a key role in the eruptive potential of volcanoes. Taking the December 2018 eruption at Mt. Etna volcano as a case study, we discuss the geochemical data streams observed. The signals indicate a long-lasting prelude stage to eruption, starting in 2017 and involving magma-fluid accumulation in the deep (>7 km bsl) reservoir, followed by pressure buildup in the system at intermediate depth (5 to 2 km bsl), 6 to 7 months before the eruption. A brief preeruptive phase marks the pressurization at 2 to 3 km below the craters. By comparing the magma and fluid recharge at depth to the measured volcanic degassing from the plume, we provide evidence that Mt. Etna was in a state of extreme overpressurization in the weeks before the onset of the eruption.