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| Titel |
Seismic Investigation of the Glacier de la Plaine Morte, Switzerland |
| VerfasserIn |
Gabi Laske, Fabian Lindner, Fabian Walter, Manuel Krage |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140476
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| Publikation (Nr.) |
 EGU/EGU2017-3872.pdf |
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| Zusammenfassung |
| Glacier de la Plaine Morte is a plateau glacier along the border between Valais and Berne
cantons. It covers a narrow elevation range and is extremely vulnerable to climate change.
During snow melt, it feeds three marginal lakes that have experienced sudden subglacial
drainage in recent years, thereby causing flooding in the Simme Valley below. Of greatest
concern is Lac des Faverges at the southeastern end of the glacier that has drained near the
end of July in recent years, with flood levels reaching capacity of flood control systems
downstream. The lake levels are carefully monitored but precise prediction has not yet been
achieved.
In the search for precursory ice fracturing to the lake drainage to improve forecast, four
seismic arrays comprised of five short-period borehole seismometers provided by
Eidgenössische Technische Hochschule (ETH), Zürich as well as fifteen 3-component
geophones from the Geophysical Instrument Pool Potsdam (GIPP) collected continuous
seismic data for about seven weeks during the summer of 2016. We present initial results on
discharge dynamics as well as changing noise levels and seismicity before, during and after
the drainage of Lac des Faverges.
Compared to previous recent years, the 2016 drainage of Lac des Faverges occurred
unusually late on August 28. With an aperture between 100 and 200 m, the small arrays
recorded many hundred ice quakes per day. A majority of the events exhibits clearly
dispersed, high-frequency Rayleigh waves at about 10 Hz and higher. A wide distribution of
events allows us to study azimuthal anisotropy and its relationship with the orientation of
glacial crevasses. |
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