Magma migration at the onset of the 2012-13 Tolbachik eruption revealed by Seismic Amplitude Ratio Analysis

In contrast of the 1975-76 Tolbachik eruption, the 2012-13 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma mo...

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Bibliographic Details
Published in:Journal of Volcanology and Geothermal Research
Main Authors: Caudron, Corentin, Taisne, Benoit, Kugaenko, Yulia, Saltykov, Vadim
Format: Article in Journal/Newspaper
Language:English
Published: 2015
Subjects:
Earth and Environmental Sciences
The 2012-13 Tolbachik eruption
Monitoring
Magma migration
Seismic Amplitude Ratio Analysis
Fissure eruption
EARTHQUAKE
KAMCHATKA
LOCATION
VOLCANO
Tolbachik
Kamchatka
Online Access:https://biblio.ugent.be/publication/8541403
http://hdl.handle.net/1854/LU-8541403
https://doi.org/10.1016/j.jvolgeores.2015.09.010
Description
Summary:In contrast of the 1975-76 Tolbachik eruption, the 2012-13 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma movement prior to this important eruption. A clear seismic migration within the seismic swarm, started 20 hours before the reported eruption onset (05:15 UTC, 26 November 2012). This migration proceeded in different phases and ended when eruptive tremor, corresponding to lava flows, was recorded (at similar to 11:00 UTC, 27 November 2012). In order to get a first order approximation of the magma location, we compare the calculated seismic intensity ratios with the theoretical ones. As expected, the observations suggest that the seismicity migrated toward the eruption location. However, we explain the pre-eruptive observed ratios by a vertical migration under the northern slope of Plosky Tolbachik volcano followed by a lateral migration toward the eruptive vents. Another migration is also captured by this technique and coincides with a seismic swarm that started 16-20 km to the south of Plosky Tolbachik at 20:31 UTC on November 28 and lasted for more than 2 days. This seismic swarm is very similar to the seismicity preceding the 1975-76 Tolbachik eruption and can be considered as a possible aborted eruption.

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