High CO2 Levels in Boreholes at El Teide Volcano Complex (Tenerife, Canary Islands): Implications for Volcanic Activity Monitoring

Emissions of CO^sub 2^ have been known for more than a hundred years as fumarolic activity at the terminal crater of El Teide volcano and as diffuse emissions at numerous water prospection drillings in the volcanic island of Tenerife. Large concentrations of CO^sub 2^ (>10% in volume) have been f...

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Bibliographic Details
Published in:Pure and applied geophysics 2004-07, Vol.161 (7), p.1519-1532
Main Authors: Soler, V., Castro-Almazán, J. A., Viñas, R. T., Eff-Darwich, A., Sánchez-Moral, S., Hillaire-Marcel, C., Farrujia, I., Coello, J., de la Nuez, J., Martín, M. C., Quesada, M. L., Santana, E.
Format: Article
Language:English
Subjects:
Boreholes
Calderas
Carbon dioxide
Degassing
Emissions
Pollution monitoring
Vertical distribution
Volcanic islands
Volcanoes
Water table
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Summary:Emissions of CO^sub 2^ have been known for more than a hundred years as fumarolic activity at the terminal crater of El Teide volcano and as diffuse emissions at numerous water prospection drillings in the volcanic island of Tenerife. Large concentrations of CO^sub 2^ (>10% in volume) have been found inside galleries, long horizontal tunnels excavated for water mining. However, CO^sub 2^ concentrations of only 2900 ppm have been observed at the surface of the central region of the island (Las Cañadas del Teide caldera). In this work we analysed CO^sub 2^ concentrations in the subsurface of Las Cañadas caldera, in an attempt to study the vertical distribution of carbon dioxide and, in particular, the low emissions at the surface. This has been done through a series of 17 vertical profiles in two deep boreholes excavated in the Caldera. We found high levels of CO^sub 2^, varying in time from 13 vol% up to 40 vol% in different profiles directly above the water table, while no significant concentrations were detected above the thermal inversion that takes places in both boreholes at approximately 100 m from the water table. Water analyses also showed high dissolved CO^sub 2^ levels in equilibrium with the air, and an average δ13C value in DIC of +4.7[per thousand] (PDB), apparently induced by fast CO^sub 2^ degassing in the bicarbonated water.[PUBLICATION ABSTRACT]
ISSN:0033-4553
1420-9136
DOI:10.1007/s00024-004-2518-1