Cross Correlation Analysis Between Volcanic Tremor And Soil CO2 Flux At Mt. Etna - Implications For Magma Dynamics
Abstract
Between November 2002 and January 2006, wide variations of CO2 flux through the soils were observed in several sites on the flanks of Mt. Etna, a basaltic volcano placed east of Sicily (Italy). CO2 flux data were recorded by automatic stations located on tectonic and volcano tectonic framework of the volcanic edifice. During the considered period, two eruptions occurred in this area: October 2002 - January 2003 and September 2004 - March 2005. CO2 flux values increased two months before the eruption onset and progressively decreased up to the background values before the end of both eruptions. As common in this area, the amplitude of the volcanic tremor also increased during the first stage of both eruptive periods. A quantitative cross correlation analysis was performed between the CO2 flux data and the overall spectral amplitude of the volcanic tremor in order to study the relationships between these two parameters. The analyses was performed on CO2 flux data filtered by the atmospheric influences: this was obtained developing an opportune filter based on both atmospheric temperature and pressure. A significant peak of the cross correlation coefficient was found, which corresponds to a lag of about 50 days of the volcanic tremor with respect to CO2 flux. This delayed similarity suggests that the volcanic tremor is linked to the shallow magma dynamics and, on the contrary, soil CO2 flux reflects more deep magma dynamics. According to this hypothesis, the volcanic tremor lag with respect to the CO2 flux might be related to the time period necessary for the magma batches ascent.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.V41A1705G
- Keywords:
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- 7280 Volcano seismology (8419);
- 8419 Volcano monitoring (7280);
- 8430 Volcanic gases;
- 8488 Volcanic hazards and risks;
- 8494 Instruments and techniques