Diffuse Degassing Rate of Carbon Dioxide and Volcanic Activity
Abstract
Volcanoes release to the atmosphere significant amount of gases through visible and non-visible manifestations. Monitoring diffuse degassing rate from volcanoes is becoming a potential geochemical tool for volcanic surveillance. During the last 15 years, ground efflux studies had been mainly focused on CO2 because it is the most abundant volatile component in magma after the H2O and the first major specie that exsolves from magma as it rises up from depth (Symonds et al., 1994; Giggenbach, 1996). Thus, diffuse CO2 emission studies is considered to be very useful for monitoring volcanic activity. This is quite evident when diffuse CO2 degassing surveys are applied on the same volcanic system following similar sampling distribution. Therefore, significant secular and spatial variations of CO2 ground efflux will imply magma movement and/or changes of seismic activity. On the contrary, this relationship between volcanic activity and diffuse CO2 degassing rate is difficult to visualize when we try to compare the total output of diffuse CO2 degassing from different volcanic systems. Major problems are mainly related with covered area, sampling distribution, sampling density, CO2 multiple origin, etc. One way to solve this difficulty is to quantify the magmatic fraction of the diffuse CO2 degassing rate, but it is a hard task since it will imply to perform hundreds of helium and carbon isotopic measurements for each survey. Statistical-graphical analysis of diffuse CO2 degassing surveys is a simple and useful tool to detect overlapping geochemical populations: background, peak and intermediate populations. Peak values of diffuse CO2 degassing are mainly due to deep perturbations of the magmatic-hydrothermal system on the surface environment. Therefore, mean values of CO2 ground efflux peak population could be a useful geochemical parameter to compare diffuse CO2 degassing rate among different volcanic systems. Mean values of peak populations related to diffuse CO2 degassing surveys from different volcanoes seem to show a strong relationship with volcanic activity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.V31A0942P
- Keywords:
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- 8494 Instruments and techniques;
- 8499 General or miscellaneous