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| Titel |
Rapid movement of frozen debris-lobes: implications for permafrost degradation and slope instability in the south-central Brooks Range, Alaska |
| VerfasserIn |
R. P. Daanen, G. Grosse, M. M. Darrow, T. D. Hamilton, B. M. Jones |
| 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 ; 12, no. 5 ; Nr. 12, no. 5 (2012-05-21), S.1521-1537 |
| Datensatznummer |
250010818
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| Publikation (Nr.) |
 copernicus.org/nhess-12-1521-2012.pdf |
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| Zusammenfassung |
| We present the results of a reconnaissance investigation of unusual debris
mass-movement features on permafrost slopes that pose a potential
infrastructure hazard in the south-central Brooks Range, Alaska. For the
purpose of this paper, we describe these features as frozen debris-lobes. We
focus on the characterisation of frozen debris-lobes as indicators of
various movement processes using ground-based surveys, remote sensing, field
and laboratory measurements, and time-lapse observations of frozen
debris-lobe systems along the Dalton Highway. Currently, some frozen
debris-lobes exceed 100 m in width, 20 m in height and 1000 m in length.
Our results indicate that frozen debris-lobes have responded to climate
change by becoming increasingly active during the last decades, resulting in
rapid downslope movement. Movement indicators observed in the field include
toppling trees, slumps and scarps, detachment slides, striation marks on
frozen sediment slabs, recently buried trees and other vegetation, mudflows,
and large cracks in the lobe surface. The type and diversity of observed
indicators suggest that the lobes likely consist of a frozen debris core,
are subject to creep, and seasonally unfrozen surface sediment is
transported in warm seasons by creep, slumping, viscous flow, blockfall and
leaching of fines, and in cold seasons by creep and sliding of frozen
sediment slabs. Ground-based measurements on one frozen debris-lobe over
three years (2008–2010) revealed average movement rates of approximately 1 cm day−1, which is substantially larger than rates measured in historic aerial
photography from the 1950s to 1980s. We discuss how climate change may
further influence frozen debris-lobe dynamics, potentially accelerating
their movement. We highlight the potential direct hazard that one of the
studied frozen debris-lobes may pose in the coming years and decades to the
nearby Trans Alaska Pipeline System and the Dalton Highway, the main artery for
transportation between Interior Alaska and the North Slope. |
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