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| Titel |
The 2002 rock/ice avalanche at Kolka/Karmadon, Russian Caucasus: assessment of extraordinary avalanche formation and mobility, and application of QuickBird satellite imagery |
| VerfasserIn |
C. Huggel, S. Zgraggen-Oswald, W. Haeberli, A. Kääb, A. Polkvoj, I. Galushkin, S. G. Evans |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 5, no. 2 ; Nr. 5, no. 2 (2005-01-31), S.173-187 |
| Datensatznummer |
250002329
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| Publikation (Nr.) |
 copernicus.org/nhess-5-173-2005.pdf |
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| Zusammenfassung |
| A massive rock/ice avalanche of about 100x106m3 volume took
place on the northern slope of the Kazbek massif, North Ossetia, Russian
Caucasus, on 20 September 2002. The avalanche started as a slope failure,
that almost completely entrained Kolka glacier, traveled down the Genaldon
valley for 20km, was stopped at the entrance of the Karmadon gorge, and was
finally succeeded by a distal mudflow which continued for another 15km. The
event caused the death of ca. 140 people and massive destruction. Several
aspects of the event are extraordinary, i.e. the large ice volume involved,
the extreme initial acceleration, the high flow velocity, the long travel
distance and particularly the erosion of a valley-type glacier, a process
not known so far. The analysis of these aspects is essential for process
understanding and worldwide glacial hazard assessments. This study is
therefore concerned with the analysis of processes and the evaluation of the
most likely interpretations. The analysis is based on QuickBird satellite
images, field observations, and ice-, flow- and thermo-mechanical
considerations. QuickBird is currently the best available satellite sensor
in terms of ground resolution (0.6 m) and opens new perspectives for
assessment of natural hazards. Evaluation of the potential of QuickBird
images for assessment of high-mountain hazards shows the feasibility for
detailed avalanche mapping and analysis of flow dynamics, far beyond the
capabilities of conventional satellite remote sensing. It is shown that the
avalanche was characterized by two different flows. The first one was
comparable to a hyperconcentrated flow and was immediately followed by a
flow with a much lower concentration of water involving massive volumes of
ice. The high mobility of the avalanche is likely related to fluidization
effects at the base of the moving ice/debris mass with high pore pressures
and a continuous supply of water due to frictional melting of ice. The paper
concludes with implications of the Kolka/Karmadon event for worldwide
glacial hazard assessments. It is emphasized that situations with large
glacierized high-mountain walls with potentially unstable glaciers within
impact distance need special attention and monitoring efforts. |
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