Dynamics of outgassing and plume transport revealed by proximal Unmanned Aerial System (UAS) measurements at Volcán Villarrica, Chile

Liu, Emma J. and Wood, Kieran and Mason, Emily M. and Edmonds, Marie and Aiuppa, Alessandro and Giudice, Gaetano and Bitetto, Marcello and Francofonte, Vincenzo and Burrow, Steve and Richardson, Thomas and Watson, Matthew and Pering, Tom D. and Wilkes, Thomas C. and McGonigle, Andrew J. S. and Velasquez, Gabriela and Melgarejo, Carlos and Bucarey, Claudia (2018) Dynamics of outgassing and plume transport revealed by proximal Unmanned Aerial System (UAS) measurements at Volcán Villarrica, Chile. Geochemistry, Geophysics, Geosystems. ISSN 1525-2027 DOI https://doi.org/10.1029/2018GC007692

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Abstract

Volcanic gas emissions are intimately linked to the dynamics of magma ascent and outgassing, and, on geological timescales, constitute an important source of volatiles to the Earth's atmosphere. Measurements of gas composition and flux are therefore critical to both volcano monitoring and to determining the contribution of volcanoes to global geochemical cycles. However, significant gaps remain in our global inventories of volcanic emissions, (particularly for CO2, which requires proximal sampling of a concentrated plume) for those volcanoes where the near‐vent region is hazardous or inaccessible. Unmanned Aerial Systems (UAS) provide a robust and effective solution to proximal sampling of dense volcanic plumes in extreme volcanic environments. Here, we present gas compositional data acquired using a gas sensor payload aboard a UAS flown at Volcán Villarrica, Chile. We compare UAS‐derived gas timeseries to simultaneous crater rim multi‐GAS data and UV camera imagery to investigate early plume evolution. SO2 concentrations measured in the young proximal plume exhibit periodic variations that are well‐correlated with the concentrations of other species. By combining molar gas ratios (CO2/SO2 = 1.48–1.68, H2O/SO2 = 67–75 and H2O/CO2 = 45–51) with the SO2 flux (142 ± 17 t/day) from UV camera images, we derive CO2 and H2O fluxes of ~150 t/day and ~2850 t/day, respectively. We observe good agreement between time‐averaged molar gas ratios obtained from simultaneous UAS‐ and ground‐based multi‐GAS acquisitions. However, the UAS measurements made in the young, less diluted plume reveal additional short‐term periodic structure that reflects active degassing through discrete, audible gas exhalations.

Item Type: Article
Uncontrolled Keywords: 2018AREP; IA74
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
08 - Green Open Access
12 - PhD
Journal or Publication Title: Geochemistry, Geophysics, Geosystems
Identification Number: https://doi.org/10.1029/2018GC007692
Depositing User: Sarah Humbert
Date Deposited: 07 Jan 2019 11:01
Last Modified: 07 Jan 2019 12:37
URI: http://eprints.esc.cam.ac.uk/id/eprint/4375

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