A CO2-gas precursor to the March 2015 Villarrica volcano eruption
Geochemistry, Geophysics, Geosystems
American Geophysical Union
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Aiuppa, A., Bitetto, M., Francofonte, V., Velasquez, G., Parra, C., Giudice, G., Liuzzo, M., et al. (2017). A CO2-gas precursor to the March 2015 Villarrica volcano eruption. Geochemistry, Geophysics, Geosystems, 18 (6), 2120-2132. https://doi.org/10.1002/2017GC006892
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 CO$_2$/SO$_2$ ratios (0.65-2.7) during November 2014-January 2015 to CO$_2$/SO$_2$ ratios up to ≈ 9 then after. The H$_2$O/CO$_2$ ratio simultaneously declined to <38 in the same temporal interval. We use results of volatile saturation models to demonstrate that this evolution toward CO$_2$-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.
volcanic gases, multi-GAS, precursor CO2/SO2 variations, Villarrica volcano, lava lakes
This work was funded by the DECADE research initiative of the DCO observatory.
External DOI: https://doi.org/10.1002/2017GC006892
This record's URL: https://www.repository.cam.ac.uk/handle/1810/265985