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Titel |
Crustal Deformation During the 2011 Volanic Crisis of El Hierro, Canary Islands, Revealed by Continuous GPS Observation |
VerfasserIn |
T. Sagiya, J. Barrancos Martinez, D. Calvo, E. Padrón, G. H. Hernandez, P. A. Hernández, N. Perez Rodriguez, J. M. P. Suárez |
Konferenz |
EGU General Assembly 2012
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 14 (2012) |
Datensatznummer |
250067898
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Zusammenfassung |
Seismo-volcnic activity of El Hierro started in the middle of July of 2011 and resulted in the
active submarine eruption after October 12 south off La Restinga, the southern tip of the
island. We have been operating one continuous GPS site on the island since 2004.
Responding to the activity, we quickly installed 5 more GPS sites. Including another site
operated by the Canary Islands Cartograhical Service (GRAFCAN) for a cartographic
purpose, we have been monitoring 7 GPS sites equipped with dual-frequency receivers. We
present the result of our crustal deformation monitoring and the magmatic activity inferred
from the deformation data. In accordance with the deformation pattern, we divide the
volcanic activity in 2011 into 4 stages. The first stage is from the middle of July
to middle of September, during which steady magmatic inflation is estimated at
the center of the island. The inflated volume of the first stage is estimated to be
about 1.3 X 107 m3 at the depth of about 5km. The second stage, which continued
until the first submarine eruption on October 12, is characterized by the accelerated
deformation due to the upward as well as southward migration of magma. Additional
inflation of about 2.1 X 107 m3 occurred in the depth range of 1-2km. The third stage
continued for about 3 weeks after the first submarine eruption. During this stage,
submarine eruption continues while no significant surface deformation is observed. It is
considered magma supply from a deeper magma chamber continued during this 3 weeks
period. Therefore, the total inflation volume during the first two stages gives the
minimum estimate for the total magma volume. Since the beginning of November
2011, many GPS sites started subsiding. However, this deflation pattern is quite
different from those in the shallow inflation stages. Horizontal deformation during this
4th stage is not significant, implying that deflation is occurring below the moho. |
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