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| Titel |
A remarkable seismo-volcanic swarm at Teide volcano (Tenerife, Canary
Islands): insight into a transient in the volcano degassing
processes |
| VerfasserIn |
Luca D'Auria, Nemesio M. Pérez, José Barrancos, Germán D. Padilla, María Asensio-Ramos, Rubén García-Hernández, Pedro A. Hernández, Eleazar Padrón |
| 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 |
250143908
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| Publikation (Nr.) |
 EGU/EGU2017-7674.pdf |
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| Zusammenfassung |
| On 02/10/2016, various seismic stations deployed in Tenerife (Canary Islands) recorded an
intense swarm of small-amplitude long-period events. Weak long-period events and tremor
were recorded also during an unrest in 2004. The Oct. 2016 swarm, however, is unique
because of its remarkable seismological features. The sequence, lasting for about 6
hours, consisted of more than 400 events and toward the end of the sequence, events
merged into a continuous tremor whose amplitude progressively vanished after 30
minutes.
We analysed waveforms from two broadband stations, located within 15 km from the
crater of Mt. Teide (the most promiment volcano of the island) and seismic phase pickings
from 3 more stations. Event waveforms show a remarkable similarity, hinting for a common
source for all the events. Probabilistic locations show that the source is located few km south
of the Mt. Teide crater. Even if the hypocentral depth is affected by a significant uncertainty,
events do not seem to be located within the shallow hydrothermal system of the
volcano.
The complex spectral analysis of the waveforms shows distinct spectral components
which are compatible with the resonance of a fracture filled with a mixture of H2O-CO2 in
supercritical conditions. The temporal pattern of amplitudes and inter-event times can be
intepreted using a chocked-flow model. The progressive opening of the fracture and the
subsequent decay of the differential pressure explains the progressive emergence of
events and the merging into a continuous, waning tremor, in the final part of the
episode.
We intepret this sequence as a transient fluid discharge episode occurring in the deep
hydrothermal system of the Tenerife volcanic system. This working hypothesis is discussed in
a more general framework involving continuous GPS data, which shows no significant
deformation and various geochemical parameters which, conversely, have shown important
anomalies before and after the swarm.
Furthermore this episode suggests the needing of a high-resolution seismic monitoring of
Tenerife and, more generally, the use of advanced data-mining technique in seismological
volcano monitoring. |
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