Bulletin of Volcanology

, Volume 74, Issue 10, pp 2435–2448 | Cite as

Diffuse volcanic degassing and thermal energy release from Hengill volcanic system, Iceland

  • Pedro A. HernándezEmail author
  • Nemesio M. Pérez
  • Thráinn Fridriksson
  • Jolie Egbert
  • Evgenia Ilyinskaya
  • Andri Thárhallsson
  • Gretar Ívarsson
  • Gestur Gíslason
  • Ingvi Gunnarsson
  • Birgir Jónsson
  • Eleazar Padrón
  • Gladys Melián
  • Toshiya Mori
  • Kenji Notsu
Research Article


We report the first detailed study of spatial variations on the diffuse emission of carbon dioxide (CO2) and hydrogen sulfide (H2S) from Hengill volcanic system, Iceland. Soil CO2 and H2S efflux measurements were performed at 752 sampling sites and ranged from nondetectable to 17,666 and 722 g m−2 day−1, respectively. The soil temperature was measured at each sampling site and used to evaluate the heat flow. The chemical composition of soil gases sampled at selected sampling sites during this study shows they result from a mixing process between deep volcanic/hydrothermal component and air. Most of the diffuse CO2 degassing is observed close to areas where active thermal manifestations occur, northeast flank of the Hengill central volcano close to the Nesjavellir power plant, suggesting a diffuse degassing structure with a SSW–NNE trend, overlapping main fissure zone and indicating a structural control of the degassing process. On the other hand, H2S efflux values are in general very low or negligible along the study area, except those observed at the northeast flank of the Hengill central volcano, where anomalously high CO2 efflux and soil temperatures were also measured. The total diffuse CO2 emission estimated for this volcanic system was about 1,526 ± 160 t day−1 of which 453 t day−1 (29.7 %) are of volcanic/hydrothermal origin. To calculate the steam discharge associated with the volcanic/hydrothermal CO2 output, we used the average H2O/CO2 mass ratio from 12 fumarole samples equal to 88.6 (range, 9.4–240.2) as a representative value of the H2O/CO2 mass ratios for Hengill fumarole steam. The resulting estimate of the steam flow associated with the gas flux is equal to 40,154 t day−1. The condensation of this steam results in thermal energy release for Helgill volcanic system of 1.07 × 1014 J day−1 or to a total heat flow of 1,237 MWt.


Diffuse CO2 emission Diffuse H2S emission Heat flux Hengill volcano 



This research was financially supported by a grant from the Spanish Ministry of Science and Technology (CGL2005-07509) as well as by the Cabildo Insular de Tenerife (Spain). Field and logistic support was also provided by ISOR and Reykjavik Energy. The authors thank one anonymous reviewer and Williams C. Evans for their constructive comments.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Pedro A. Hernández
    • 1
    • 2
    Email author
  • Nemesio M. Pérez
    • 1
    • 2
  • Thráinn Fridriksson
    • 3
  • Jolie Egbert
    • 3
    • 7
  • Evgenia Ilyinskaya
    • 3
    • 9
  • Andri Thárhallsson
    • 3
  • Gretar Ívarsson
    • 4
  • Gestur Gíslason
    • 4
    • 8
  • Ingvi Gunnarsson
    • 4
  • Birgir Jónsson
    • 5
  • Eleazar Padrón
    • 1
    • 2
  • Gladys Melián
    • 1
    • 2
  • Toshiya Mori
    • 6
  • Kenji Notsu
    • 6
    • 10
  1. 1.Environmental Research DivisionInstituto Tecnológico y de Energías Renovables (ITER)Granadilla de AbonaSpain
  2. 2.Instituto Volcanológico de Canarias (INVOLCAN)Puerto de La CruzSpain
  3. 3.Iceland GeoSurvey (ISOR)ReykjavíkIceland
  4. 4.Reykjavik Energy (Orkuveita Reykjavíkur)ReykjavíkIceland
  5. 5.Civil and Environmental Engineering DepartmentUniversity of IcelandReykjavíkIceland
  6. 6.Geochemical Research Center, Graduate School of ScienceThe University of TokyoTokyoJapan
  7. 7.Helmholtz Centre PotsdamGFZ German Research Centre for GeosciencesPotsdamGermany
  8. 8.Reykjavik GeothermalReykjavíkIceland
  9. 9.Icelandic Meteorological OfficeReykjavíkIceland
  10. 10.Center for Integrated Research and Education of Natural Hazards (CIREN)Shizuoka UniversityShizuokaJapan

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