Monitoring crustal changes at volcanoes by seismic noise interferometry: Mt. Etna case of study
Abstract
In this work, we analysed the seismic noise recorded at Mt. Etna by 18 stations during the interval 2007-2015 in the frequency band 0.1-0.3 Hz, chosen to avoid contamination from volcanic tremor. Variations in time of medium seismic velocity in the range - 0.8 to 0.8% were found, mostly affecting the stations located on the volcano summit and flanks. Based on the investigated frequency content, the Δv/v changes took place from the surface to a depth of 4.5-6.5 km. To identify the source mechanism of the observed medium changes, the variations were quantitatively compared by wavelet transform coherence with volcano-tectonic and meteorological parameters. A significant relationship with meteorological parameters with seasonal periodicity (especially air temperature and snow loading) was found, probably caused by thermo-elastic strain and increasing-decreasing surface loading cycles. Moreover, a sharp medium velocity decrease, taking place in mid-December 2009 and clearly time-related to the largest volcano-tectonic strain release phenomenon of the investigated period, was also found. Such a velocity decrease was interpreted as resulting from ascent of fluids and gas exsolution taking place at the same time as the volcano-tectonic swarm.
- Publication:
-
Journal of Volcanology and Geothermal Research
- Pub Date:
- May 2017
- DOI:
- 10.1016/j.jvolgeores.2017.03.023
- Bibcode:
- 2017JVGR..337..165C
- Keywords:
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- Seismic noise interferometry;
- Mt. Etna;
- Meteorological parameters;
- Volcanic tremor