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| Titel |
The geomorphological effect of cornice fall avalanches in the Longyeardalen valley, Svalbard |
| VerfasserIn |
M. Eckerstorfer, H. H. Christiansen, L. Rubensdotter, S. Vogel |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 7, no. 5 ; Nr. 7, no. 5 (2013-09-05), S.1361-1374 |
| Datensatznummer |
250085153
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| Publikation (Nr.) |
 copernicus.org/tc-7-1361-2013.pdf |
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| Zusammenfassung |
| The study of snow avalanches and their geomorphological effect in the
periglacial parts of the cryosphere is important for enhanced
geomorphological process understanding as well as hazard-related studies.
Only a few field studies, and particularly few in the High Arctic, have
quantified avalanche sedimentation. Snow avalanches are traditionally ranked
behind rockfall in terms of their significance for mass-wasting processes of
rockslopes. Cornice fall avalanches are at present the most dominant snow
avalanche type at two slope systems, called Nybyen and Larsbreen, in the
valley Longyeardalen in central Svalbard. Both slope systems are on northwest-facing
lee slopes underneath a large summit plateau, with annual cornices forming on
the top. High-frequency and magnitude cornice fall avalanching is observed by
daily automatic time-lapse photography. In addition, rock debris
sedimentation by cornice fall avalanches was measured directly in permanent
sediment traps or by snow inventories. The results from a maximum of seven years of
measurements in a total of 13 catchments show maximum mean rock debris
sedimentation rates ranging from 8.2 to 38.7 kg m−2 at Nybyen, and
from 0.8 to 55.4 kg m−2 at Larsbreen. Correspondingly, avalanche
fan surfaces accreted from 2.6 to 8.8 mm yr−1 at Nybyen, and from 0.2
to 13.9 mm yr−1 at Larsbreen. This comparably efficient rockslope mass
wasting is due to collapsing cornices producing cornice fall avalanches
containing large amounts of rock debris throughout the entire winter. The
rock debris of different origin stems from the plateau crests, the adjacent
free rock face and the transport pathway, accumulating distinct avalanche
fans at both slope systems. Cornice fall avalanche sedimentation also
contributed to the development of a rock glacier at the Larsbreen site during
the Holocene. We have recorded present maximum rockwall retreat rates of
0.9 mm yr−1 at Nybyen, but as much as 6.7 mm yr−1 at Larsbreen,
while average Holocene rockwall retreat rates of 1.1 mm yr−1 at
Nybyen have been determined earlier. As cornice fall avalanches are the
dominant type of avalanche in central Svalbard, the related geomorphological
effect is assumed to be of significance at periglacial landscape scale. A
climate-induced shift in prevailing winter wind direction could change the
rockslope sedimentation effectively by changing the snow avalanche activity. |
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