TY  - JOUR
PY  - 2017//
TI  - Magmatic gas percolation through the old lava dome of El Misti volcano
JO  - Bulletin of volcanology
A1  - Moussallam, Yves
A1  - Peters, Nial
A1  - Masias, Pablo
A1  - Apaza, Fredy
A1  - Barnie, Talfan
A1  - Ian Schipper, C.
A1  - Curtis, Aaron
A1  - Tamburello, Giancarlo
A1  - Aiuppa, Alessandro
A1  - Bani, Philipson
A1  - Giudice, Gaetano
A1  - Pieri, David
A1  - Davies, Ashley Gerard
A1  - Oppenheimer, Clive
SP  - e46
EP  - e46
VL  - 79
IS  - 6
N2  - 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 H<sub>2</sub>O/SO<sub>2</sub> molar ratio of 32 ± 3, a CO<sub>2</sub>/SO<sub>2</sub> molar ratio of 2.7 ± 0.2, a H<sub>2</sub>S/SO<sub>2</sub> molar ratio of 0.23 ± 0.02 and a H<sub>2</sub>/SO<sub>2</sub> molar 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.<br><br>© The Author(s) 2017.<p />  <p>Language: en</p>
LA  - en
SN  - 0258-8900
UR  - http://dx.doi.org/10.1007/s00445-017-1129-5
ID  - ref1
ER  -