Magmatic gas percolation through the old lava dome of El Misti volcano

Alessandro Aiuppa, Philipson Bani, Giancarlo Tamburello, Gaetano Giudice, C. Ian Ian Schipper, Nial Peters, Ashley Gerard Davies, Talfan Barnie, Aaron Curtis, Yves Moussallam, Pablo Masias, Fredy Apaza, Alessandro Aiuppa, David Pieri, Clive Oppenheimer

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Abstract

The proximity of the major city of Arequipa to El Misti has focused attention on the hazards posed by the active volcano. Since its last major eruption in the fifteenth century, El Misti has experienced a series of modest phreatic eruptions and fluctuating fumarolic activity. Here, we present the first measurements of the compositions of gas emitted from the lava dome in the summit crater. The gas composition is found to be fairly dry with a H2O/SO2molar ratio of 32 ± 3, a CO2/SO2molar ratio of 2.7 ± 0.2, a H2S/SO2molar ratio of 0.23 ± 0.02 and a H2/SO2molar ratio of 0.012 ± 0.002. This magmatic gas signature with minimal evidence of hydrothermal or wall rock interaction points to a shallow magma source that is efficiently outgassing through a permeable conduit and lava dome. Field and satellite observations show no evolution of the lava dome over the last decade, indicating sustained outgassing through an established fracture network. This stability could be disrupted if dome permeability were to be reduced by annealing or occlusion of outgassing pathways. Continued monitoring of gas composition and flux at El Misti will be essential to determine the evolution of hazard potential at this dangerous volcano.
Original languageEnglish
Number of pages11
JournalBulletin of Volcanology
Volume79
Publication statusPublished - 2017

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology

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    Aiuppa, A., Bani, P., Tamburello, G., Giudice, G., Ian Schipper, C. I., Peters, N., Davies, A. G., Barnie, T., Curtis, A., Moussallam, Y., Masias, P., Apaza, F., Aiuppa, A., Pieri, D., & Oppenheimer, C. (2017). Magmatic gas percolation through the old lava dome of El Misti volcano. Bulletin of Volcanology, 79.