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| Titel |
Short-term variations of diffuse CO2 emission from the summit crater of Teide volcano, Tenerife, Canary Islands |
| VerfasserIn |
Gladys V. Melián, Stephany Ocampo, Andrew Nisbet, Samara McKnight, Tania Monzón, María Asensio-Ramos, Mar Alonso, Fátima Rodriguez, Marta García-Merino, Cecilia Amonte, Nemesio M. Pérez |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143313
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| Publikation (Nr.) |
 EGU/EGU2017-7020.pdf |
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| Zusammenfassung |
| Teide volcano in Tenerife, Canary Islands, is characterized by the presence of a weak
fumarolic system, steamy ground, and high rates of diffuse CO2 degassing all around this
area. The temperature of the fumaroles (83˚ C) corresponds to the boiling point of water at
discharge conditions. Previous diffuse CO2 surveys have shown to be an important tool to
detect early warnings of possible impending volcanic unrests at Tenerife Island (Melián et
al., 2012; Pérez et al., 2013). During June, July and August 2016, twelve soil gas
surveys were performed at the summit crater of Teide volcano in order to evaluate
short-term variations of diffuse CO2 degassing pattern. Soil CO2 efflux and soil
temperature were always measured at the same 38 observation sites homogeneously
distributed within an area of about 6,972 m2 inside the summit crater. Soil CO2
diffuse effluxes were estimated according to the accumulation chamber method
and using a non-dispersive infrared (NDIR) LICOR-820 CO2analyzer. Soil CO2
efflux values presented a range from non-detectable (∼0.5 g⋅m−2⋅d−1) to 10.8
kg⋅m−2⋅d−1, with an average value of 2.7 kg⋅m−2⋅d−1, while soil temperature
ranged from 13.1 to 83.6˚ C with a mean value of 55.6˚ C. Sequential Gaussian
simulations (sGs) were used for mapping and estimate the volcanic diffuse CO2
emission at each survey. The highest values of diffuse CO2 efflux were measured along
the east (>8 kg⋅m−2⋅d−1) and west (>5 kg⋅m−2⋅d−1) sectors of the crater. Areas
with highest diffuse CO2 effluxes were also characterized by a relatively high soil
temperature (>60˚ C) and by an intense hydrothermal alteration. Weekly diffuse CO2
emission variations from the summit crater during the study period showed a range
between 13.5 and 24.7 t⋅d−1 with an average value of 18.9 t⋅d−1. During these 3
months, the seismic activity rate was about 10 seismic events per month registered by
the Instituto Geográfico Nacional (IGN; http://www.ign.es). We compared these
observed weekly variations with monthly variations of a longer period with similar
seismic rate such as 2014 (about 8 seismic events per month, and values ranged
from 15.6 to 22.4 t⋅d−1, and an average value of 19.0 t⋅d−1. These values are in the
same order than the observed during our study. However, for a longer period of
observation, from 1999 to 2010, diffuse CO2 emission rates varied from 2.2 to 36.3 t⋅d−1,
with a mean value of 15.7 t⋅d−1 (Melián et al., 2012). The long-term variations
observed in the diffuse CO2 emission rates during this period of 10 years were
significantly higher than short-term variations observed in the period of study. It is
also important to note that the volcanic-seismic crisis of 2004 occurred with an
increase on the CO2 emission from Teide summit crater (Melián et al., 2012). This
study shows that during periods of seismic tranquility, diffuse CO2 emission rates
will not suffer significant variations, whether performed on a weekly or monthly
basis.
References:
Melián et al., 2012. Bull. Volcanol. DOI 10.1007/s00445-012-0613-1
Pérez et al., 2013. J. Geol. Soc. DOI 10.1144/jgs2012-125
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