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| Titel |
Spatial and temporal variations of diffuse CO2 degassing at the Tenerife North--South Rift Zone (NSRZ) volcano (Canary Islands) during the period 2002-2016 |
| VerfasserIn |
Fátima Rodriguez, John J. K. McCollum, Elijah D. M. Orland, José Barrancos, Germán D. Padilla, David Calvo, 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 |
250143475
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| Publikation (Nr.) |
 EGU/EGU2017-7196.pdf |
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| Zusammenfassung |
| Subaerial volcanic activity on Tenerife (2034 km2), the largest island of the Canary
archipelago, started 14 My ago and 4 volcanic eruptions have occurred in historical times
during the last 300 years. The main volcano-structural and geomorphological features of
Tenerife are (i) the central volcanic complex, nowadays formed by Las Cañadas caldera, a
volcanic depression measuring 16×9 km that resulted from multiple vertical collapses and
partially filled by post-caldera volcanic products and (ii) the triple junction-shaped rift
system, formed by numerous aligned monogenetic cones. Up to 297 mafic monogenetic
cones have been recognized on Tenerife, and they represent the most common eruptive
activity occurring on the island during the last 1 My (Dóniz et al., 2008). The North–South
Rift Zone (NSRZ) of Tenerife comprises at least 139 cones. The main structural
characteristic of the NSRZ of the island is an apparent absence of a distinct ridge, and a
fan shaped distribution of monogenetic cones. Since there are currently no visible
gas emissions at the NSRZ, diffuse degassing surveys have become an important
geochemical tool for the surveillance of this volcanic system. Five diffuse CO2 degassing
surveys have been carried out at NSRZ of Tenerife since 2002, the last one in the
summer period of 2016, to evaluate the spatio-temporal variations of CO2 degassing
as a volcanic surveillance tool for the NSRZ of Tenerife. At each survey, around
600 sampling sites were selected to cover homogenously the study area (325 km2)
using the accumulation chamber method. The diffuse CO2 output ranged from 78 to
707 t/d in the study period, with the highest emission rate measured in 2015. The
backgroung emission rate was estimated in 300 t/d. The last results the soil CO2 efflux
values ranged from non-detectable up to 24.7 g m−2 d−1. The spatial distribution
map, constructed following the sequential Gaussian simulation (sGs) procedure,
showed the highest CO2 values as multiple isolated anomalies and did not show a
clear relation with the main volcano-structural features of the area. The CO2 output
released to the atmosphere in a diffuse way has been estimated at 524 t d−1, which
represents a value lower than the previous one (707 t d−1 at summer of 2015) but
higher than the background emission rate. These changes in the temporal series
confirm the need of periodic diffuse emission surveys in the area as a powerful
volcanic surveillance tool in volcanic systems where visible gas emanations are
absent.
References:
Dóniz et al., 2008. J. Volcanol. Geotherm. Res. 173, 185. |
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