June 18-21, 2006
A landslide inventory was carried out for the Little Salmon Lake area, Yukon Territory, Canada, in response to observations of several new landslides in the area, suspected to be the result of degrading permafrost. The largest of these landslides, the Magundy River bi-modal flow-slide, has progressed over the last decade until it now involves over 1x106 m3 of material. The inventory is based on terrain mapping and field work, and includes multiple landslide types. The field work provided the opportunity to examine the slides, ground truth the map, and to examine the progression of the landslide, as well as the massive ground ice exposed in the scarps of the currently active slides. Permafrost degradation can be driven by anthropogenic or natural agents of change. The study investigated natural agents of change, as anthropogenic sources are not active, due to the remote and undeveloped nature of the area. Temperature data from the area indicates a warming trend of 3ºC over the last 40 years, supporting the theory that climate amelioration is one of the major factors generating the new activation of landslides in the area. Susceptibility maps were developed to examine the potential for landslide initiation due to permafrost degradation. The most important data required for this work is the distribution of ground ice. In the absence of any borehole or geophysical data in the area, or generally of detailed mapping of permafrost distribution in the Canadian north, an expert system was used to predict the location of ground ice. Therefore, the landslide susceptibility maps are very dependent on the accuracy of this map. Should development in the valley proceed, more accurate landslide susceptibility mapping would be required. Due to the importance of the ground ice distribution and condition, it would be recommended that data be collected to accurately map the ice and therefore to improve the accuracy of the prediction of possible landslides.
R. Lyle and D. Jean Hutchinson, "Influence of Degrading Permafrost on Landsliding Processes: Little Salmon Lake, Yukon Territory, Canada" in "Geohazards", Professor Farrokh Nadim, International Centre for Geohazards, Oslo, Norway; Dr. Rudolf Pöttler, Managing Director, ILF - Consulting Engineers, Innsbruck, Austria; Professor Herbert Einstein, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; Professor Herbert Klapperich, TU Bergakademie Freiberg, Institut für Geotechnik, Freiberg, Germany; Professor Steven Kramer, University of Washington, Seattle, Washington, USA Eds, ECI Symposium Series, (2006). http://dc.engconfintl.org/geohazards/4