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| Titel |
Eighteen years of geochemical monitoring at the oceanic active volcanic island of El Hierro (Canary Islands, Spain) |
| VerfasserIn |
María Asensio-Ramos, Mar Alonso, Emerson Sharp, Hannah Woods, José Barrancos, Nemesio M. Pérez |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128419
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| Publikation (Nr.) |
 EGU/EGU2016-8406.pdf |
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| Zusammenfassung |
| We report herein the latest results of a diffuse CO2 efflux survey at El Hierro volcanic system
carried out during the summer period of 2015 to constrain the total CO2 output from the
studied area a during post-eruptive period. El Hierro Island (278 km2) is the youngest and the
SW-most of the Canary Islands. On July 16, 2011, a seismic-volcanic crisis started with the
occurrence of more than 11,900 seismic events and significant deformation along the island.
On October 10, 2011, the dominant character of seismicity changed dramatically from
discrete earthquakes to continuous tremor, a clear indication that magma was rapidly
approaching the surface immediately before the onset of the eruption, October 12.
Eruption was declared over on 5 March, 2012. In order to monitor the volcanic activity
of El Hierro Island, from 1998 to 2015 diffuse CO2 emission studies have been
performed at El Hierro volcanic system in a yearly basis (∼600 observation sites)
according to 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. During the eruption period, soil CO2 efflux values range from
non-detectable (∼0.5 g m−2 d−1) up to 457 g m−2 d−1, reaching in November 27,
2011, the maximum CO2 output estimated value of all time series, 2,398 t d−1, just
before the episodes of maximum degassing observed as vigorous bubbling at the sea
surface and an increment in the amplitude of the tremor signal. During the 2015
survey, soil CO2 efflux values ranged from non-detectable up to 41 g m−2 d−1.
The spatial distribution of diffuse CO2 emission values seemed to be controlled by
the main volcano structural features of the island. The total diffuse CO2 output
released to atmosphere was estimated at 575 ± 24 t d−1, value slightly higher that the
background CO2 emission estimated at 422 t d−1 (Melián et al., 2014). The above
data demonstrate that discrete surveys of diffuse CO2 emission provide important
information to optimize the early warning system in volcano monitoring programs and to
monitor the evolution of an ongoing volcanic eruption, even though it is a submarine
eruption.
References:
Melián et al., 2014. J. Geophys. Res. DOI: 10.1002/2014JB011013. |
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