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Titel |
Seventeen years of monitoring diffuse CO2 emission from the Tenerife North–West Rift Zone (NWRZ) volcano, Canary Islands |
VerfasserIn |
Germán D. Padilla, Bethany J. Evans, Aaron R. Provis, María Asensio, Mar Alonso, David Calvo, Pedro Hernandez, 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 |
250143505
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Publikation (Nr.) |
EGU/EGU2017-7231.pdf |
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Zusammenfassung |
Tenerife together and Gran Canaria are the central islands of the Canarian archipelago,
which have developed a central volcanic complex characterized by the eruption of
differentiated magmas. Tenerife is the largest of the Canary Islands (2100 km2) and
at present, the North-West Rift-Zone (NWRZ) is one of the most active volcanic
structures of the three volcanic rift-zone of the island, which has hosted two historical
eruptions (Arenas Negras in 1706 and Chinyero in 1909). In order to monitor the
volcanic activity of NWRZ, since the year 2000, 49 soil CO2 efflux surveys have
been performed at NWRZ (more than 300 observation sites each one) to evaluate
the temporal an spatial variations of CO2 efflux and their relationships with the
volcanic-seismic activity. Measurements were performed in accordance with the
accumulation chamber method. Spatial distribution maps were constructed following
the sequential Gaussian simulation (sGs) procedure. To quantify the total CO2
emission from the studied area, 100 simulations for each survey have been performed.
We report herein the results of the last diffuse CO2 efflux surveys at the NWRZ
undertaken in July and October 2016 to constrain the total CO2 output from the
studied area. During July and October 2016 surveys, soil CO2 efflux values ranged
from non-detectable up to 32.4 and 53.7 g m−2 d−1, respectively. The total diffuse
CO2 output released to atmosphere were estimated at 255 ± 9 and 338 ± 18 t d−1,
respectively, values higher than the background CO2 emission estimated on 144 t
d−1. Since 2000, soil CO2 efflux values have ranged from non-detectable up to
141 g m−2 d−1, with the highest values measured in May 2005 whereas total CO2
output ranged between 52 and 867 t d−1. Long-term variations in the total CO2
output have shown a temporal correlation with the onsets of seismic activity at
Tenerife, supporting unrest of the volcanic system, as is also suggested by anomalous
seismic activity recorded in the studied area during April 22-29, 2004 and also
during October 2-3, 2016. Spatial distribution of soil CO2 efflux values also showed
changes in magnitude and amplitude, with higher CO2 efflux values measured along a
trending WNW-ESE zone. Subsurface magma movement is proposed as a cause
for the observed changes in the total output of diffuse CO2 emission as well as
for the spatial distribution of soil CO2 efflux. The increasing trend of total CO2
output suggests increasing pressurization of the volcanic-hydrothermal system, a
mechanism capable of triggering dyke intrusion along the NWRZ of Tenerife in the near
future or futures changes in the seismicity. This study demonstrates the importance
of performing soil CO2 efflux surveys as an effective surveillance volcanic tool. |
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