We present here the first volcanic gas compositional time-series taken prior to a paroxysmal eruption of Villarrica volcano (Chile). Our gas plume observations were obtained using a fully autonomous Multi-component Gas Analyser System (Multi-GAS) in the 3 month-long phase of escalating volcanic activity that culminated into the 3 March 2015 paroxysm, the largest since 1985. Our results demonstrate a temporal evolution of volcanic plume composition, from low CO2/SO2ratios (0.65-2.7) during November 2014-January 2015 to CO2/SO2ratios up to ≈ 9 then after. The H2O/CO2ratio simultaneously declined to <38 in the same temporal interval. We use results of volatile saturation models to demonstrate that this evolution toward CO2-enriched gas was likely caused by unusual supply of deeply sourced gas bubbles. We propose that separate ascent of over-pressured gas bubbles, originating from at least 20-35 MPa pressures, was the driver for activity escalation toward the 3 March climax.

Aiuppa, A., Bitetto, M., Francofonte, V., Velasquez, G., Parra, C., Giudice, G., et al. (2017). A CO2-gas precursor to the March 2015 Villarrica volcano eruption. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS, 18(6), 2120-2132 [10.1002/2017GC006892].

A CO2-gas precursor to the March 2015 Villarrica volcano eruption

Aiuppa, Alessandro;Bitetto, Marcello;
2017-01-01

Abstract

We present here the first volcanic gas compositional time-series taken prior to a paroxysmal eruption of Villarrica volcano (Chile). Our gas plume observations were obtained using a fully autonomous Multi-component Gas Analyser System (Multi-GAS) in the 3 month-long phase of escalating volcanic activity that culminated into the 3 March 2015 paroxysm, the largest since 1985. Our results demonstrate a temporal evolution of volcanic plume composition, from low CO2/SO2ratios (0.65-2.7) during November 2014-January 2015 to CO2/SO2ratios up to ≈ 9 then after. The H2O/CO2ratio simultaneously declined to <38 in the same temporal interval. We use results of volatile saturation models to demonstrate that this evolution toward CO2-enriched gas was likely caused by unusual supply of deeply sourced gas bubbles. We propose that separate ascent of over-pressured gas bubbles, originating from at least 20-35 MPa pressures, was the driver for activity escalation toward the 3 March climax.
2017
Aiuppa, A., Bitetto, M., Francofonte, V., Velasquez, G., Parra, C., Giudice, G., et al. (2017). A CO2-gas precursor to the March 2015 Villarrica volcano eruption. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS, 18(6), 2120-2132 [10.1002/2017GC006892].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/251161
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