title: Magmas near the critical degassing pressure drive volcanic unrest towards a critical state.
abstract: During the reawaking of a volcano, magmas migrating through the shallow crust have to pass through hydrothermal fluids and rocks. The resulting magma-hydrothermal interactions are still poorly understood, which impairs the ability to interpret volcano monitoring signals and perform hazard assessments. Here we use the results of physical and volatile saturation models to demonstrate that magmatic volatiles released by decompressing magmas at a critical degassing pressure (CDP) can drive volcanic unrest towards a critical state. We show that, at the CDP, the abrupt and voluminous release of H2O-rich magmatic gases can heat hydrothermal fluids and rocks, triggering an accelerating deformation that can ultimately culminate in rock failure and eruption. We propose that magma could be approaching the CDP at Campi Flegrei, a volcano in the metropolitan area of Naples, one of the most densely inhabited areas in the world, and where accelerating deformation and heating are currently being observed.
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Bologna, via D. Creti 12, 40128 Bologna, Italy.
authors.forename: Giovanni
authors.identifier: 0000-0002-0628-8055
authors.initials: G
authors.lastname: Chiodini
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Palermo, via U. La Malfa 153, 90146 Palermo, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Paonita
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Palermo, via U. La Malfa 153, 90146 Palermo, Italy.|DiSTeM, Università di Palermo, via Archirafi 36, 90123 Palermo, Italy.
authors.forename: Alessandro
authors.identifier: 0000-0002-0254-6539
authors.initials: A
authors.lastname: Aiuppa
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Bologna, via D. Creti 12, 40128 Bologna, Italy.
authors.forename: Antonio
authors.identifier: 0000-0002-4987-6471
authors.initials: A
authors.lastname: Costa
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Napoli Osservatorio Vesuviano, via Diocleziano 328, 80124 Napoli, Italy.
authors.forename: Stefano
authors.identifier: 0000-0002-8522-6695
authors.initials: S
authors.lastname: Caliro
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, sezione di Napoli Osservatorio Vesuviano, via Diocleziano 328, 80124 Napoli, Italy.
authors.forename: Prospero
authors.initials: P
authors.lastname: De Martino
authors.affiliation: Dipartimento di Scienze, Università Roma Tre, Largo San Leonardo Murialdo, 1, 00146 Roma, Italy.
authors.forename: Valerio
authors.initials: V
authors.lastname: Acocella
authors.affiliation: Université de Savoie Mont Blanc, Chambéry 73000, France.|CNRS, ISTerre, F-73376 Le Bourget du Lac, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Vandemeulebrouck