The Most Intense Deflation of the Last Two Decades at Mt. Etna: The 2019–2021 Evolution of Ground Deformation and Modeled Pressure Sources. Issue 6 (21st March 2022)

• Record Type: Journal Article
• Authors: Bruno, V.; Aloisi, M.; Gambino, S.; Mattia, M.; Ferlito, C.; Rossi, M.
• Is Part Of: Geophysical research letters. Volume 49:Issue 6(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-21
• Subjects: volcanic ground deformations -- volcanic pressure sources modeling -- GNSS and tilt analysis; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL095195
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We analyze Global Navigation Satellite System (GNSS) and tilt data from the permanent monitoring networks of Etna volcano starting just after the 24 December 2018 eruption to an unusual two‐month period of deflation in February–March, 2021, which coincided with the occurrence of 17 lava fountain episodes. Based on changes in slope in the GNSS displacement time series, we divide the period starting 7 months after the eruption into five phases, spanning the continued inflation of the edifice punctuated by short periods of effusive and strombolian activity (four phases) and a 2‐month phase of intensive deflation. Our model indicates a progressive deepening of the internal pressure sources followed by a fast ascending source starting two‐months before the first 2021 paroxysms. We explain these results in light of a recent volcanological model on the nature and behavior of magma ascending through the Etnean feeding system. Plain Language Summary: On 16 February 2021, an eruptive phase characterized by 17 paroxysms from the Southeast Crater began at Etna volcano, producing km‐high volcanic plumes and large tephra fallouts, causing hazard to air traffic and impacting inhabited areas. The paroxysms caused the most intense deflation of the volcanic edifice in the last two decades. We model both the inflation phases preceding the paroxysms and the period of deflation to investigate the internal pressure sources. Data suggest that the volcanic pressure source deepens progressively, during the recharging phases, and ascends only 2 months before the start of the paroxysms. A complex interaction between the high amounts of volatile elements dissolved in the molten rock and the arrival of new melt intrusions from depth allowed us to explain this singular behavior. Key Points: The February–March 2021 paroxysms at Etna produced the most intense deflation of the volcanic edifice in the last two decades The different phases of inflation preceding the paroxysms were accompanied by a deepening over time of the internal pressure sources The volcanic pressure source ascended rapidly two months before the first 2021 paroxysm, associated with an increase of volcanic gas flux