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| Titel |
Variations of the BrO/SO2 ratios from Tungurahua volcano, Ecuador |
| VerfasserIn |
Simon Warnach, Peter Lübcke, Florian Dinger, Nicole Bobrowski, Silvana Hidalgo, Santiago Arellano, Jean Battaglia, Bo Galle, Christoph Hörmann, Mario Ruiz, Leif Vogel, Thomas Wagner, Ulrich Platt |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122046
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| Publikation (Nr.) |
 EGU/EGU2016-972.pdf |
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| Zusammenfassung |
| The amount and composition of volcanic gas emissions can yield information about
magmatic processes. Apart from the SO2 emission rate, which is used as a widespread tool in
monitoring volcanoes, the molar ratio of BrO/SO2 in a volcanic plume has shown the
potential for interpreting volcanic activity. The evaluation of long-term spectral data collected
with UV-scanning spectrometers through the Network for Observation of Volcanic and
Atmospheric Change (NOVAC) using the DOAS technique can help to obtain a better
understanding of the BrO/SO2 molar ratio and its correlation to magmatic processes. BrO and
SO2 emissions as well as the BrO/SO2 ratio have been successfully retrieved from NOVAC
data at Nevado del Ruiz (Colombia), where a decrease of the BrO/SO2 ratio was observed
prior to a large eruption.
We apply this evaluation algorithm to determine the plume composition of Tungurahua
volcano, Ecuador, which is part of NOVAC since 2007. Different from Nevado del Ruiz the
retrieved column densities of SO2 and BrO at Tungurahua are typically more than a factor of
two lower during the respective period of observation. In addition, changes in the volcanic
activity appear on a smaller timescale, as Tungurahua displays a succession of activity and
quiescence phases. In order to still obtain robust BrO/SO2 ratios at Tungurahua, it is
necessary to improve the data evaluation as well as applying a more sophisticated scheme to
calculate the BrO/SO2 ratio. By combining both methods we create a time series of the
BrO/SO2 ratio for several eruptive phases between 2007 and 2014. The ratio shows
values between 2 and 8 × 10−5. The variation of the BrO/SO2 ratio during these
eruptive phases is compared to seismic data and volcanological phenomenological
observations as well as satellite and ground based SO2 measurements. During several
eruptive phases we observe an increase in the BrO/SO2 ratio on the transition from
high explosive activity to low explosive activity. During the eruptive phase from
November 2010 to January 2011 for example, we observe a BrO/SO2 ratio around
5.1 × 10−5 during the initial period characterized by high explosive activity and an
increased ratio of around 8.5 × 10−5 during the following period with low explosive
activity. |
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