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Volcanic signatures in time gravity variations during the volcanic unrest on El Hierro (Canary Islands)
Author(s) -
SainzMaza Aparicio S.,
Arnoso Sampedro J.,
Gonzalez Montesinos F.,
Martí Molist J.
Publication year - 2014
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2013jb010795
Subject(s) - geology , volcano , seismology , magma , unrest , intrusion , gravimeter , submarine volcano , geophysics , geochemistry , casing , politics , political science , law
Gravity changes occurring during the initial stage of the 2011–2012 El Hierro submarine eruption are interpreted in terms of the preeruptive signatures during the episode of unrest. Continuous gravity measurements were made at two sites on the island using the relative spring gravimeter LaCoste and Romberg gPhone‐054. On 15 September 2011, an observed gravity decrease of 45 μGal, associated with the southward migration of seismic epicenters, is consistent with a lateral magma migration that occurred beneath the volcanic edifice, an apparently clear precursor of the eruption that took place 25 days later on 10 October 2011. High‐frequency gravity signals also appeared on 6–11 October 2011, pointing to an occurring interaction between a magmatic intrusion and the ocean floor. These important gravity changes, with amplitudes varying from 10 to −90 μGal, during the first 3 days following the onset of the eruption are consistent with the northward migration of the eruptive focus along an active eruptive fissure. An apparent correlation of gravity variations with body tide vertical strain was also noted, which could indicate that concurrent tidal triggering occurred during the initial stage of the eruption.