Kinematics of steep bedrock permafrost

被引:77
作者
Hasler, Andreas [1 ]
Gruber, Stephan [1 ]
Beutel, Jan [2 ]
机构
[1] Univ Zurich, Dept Geog, CH-8057 Zurich, Switzerland
[2] ETH, Comp Engn & Networks Lab, CH-8092 Zurich, Switzerland
基金
瑞士国家科学基金会;
关键词
SLOPE STABILITY; ICE SEGREGATION; ROCK SLOPES; ALPINE ROCK; TEMPERATURE; ALPS; MECHANISMS; FRACTURE; COLD;
D O I
10.1029/2011JF001981
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
The mechanisms that control climate-dependent rockfall from permafrost mountain slopes are currently poorly understood. In this study, we present the results of an extensive rock slope monitoring campaign at the Matterhorn (Switzerland) with a wireless sensor network. A negative dependency of cleft expansion relative to temperature was observed at all clefts for the dominant part of the year. At many clefts this process is interrupted by a period with increased opening and shearing activity in the summer months. More specific, this period lasts from sustained melting within the cleft to the first freezing in autumn. Based on these empirical findings we identify two distinct process regimes governing the cleft motion observed. Combining current theories with laboratory evidence on rock slope movement and stability, we postulate that (1) the negative temperature-dependency is caused by thermomechanical forcing and is reinforced by cryogenic processes during the freezing period and, (2) the enhanced movement in summer originates from a hydro-thermally induced strength reduction in clefts containing perennial ice. It can be assumed that the irreversible part of the process described in (1) slowly modifies the geometric settings and cleft characteristics of permafrost rock slopes in the long term. The thawing related processes (2) can affect stability within hours or weeks. Such short-term stability minima may activate rock masses subject to the slow changes and lead to acceleration and failure. Citation: Hasler, A., S. Gruber, and J. Beutel (2012), Kinematics of steep bedrock permafrost, J. Geophys. Res., 117, F01016, doi:10.1029/2011JF001981.
引用
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页数:17
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