Active Layer Detachment Slides and Retrogressive Thaw Slumps Susceptibility Mapping for Current and Future Permafrost Distribution, Yukon Alaska Highway Corridor

Abstract

The Yukon portion of the Alaska Highway Corridor traverses the discontinuous permafrost zone. Air-photos and high resolution satellite imagery were used to produce an updated landslide inventory (2013) that identified 1,600 landslides in the corridor. Landslide susceptibility models were developed for the corridor for two types of landslides triggered in permafrost, active layer detachment slides (ALD) and retrogressive thaw slumps (RTS), which comprise about 3 % of the inventory. A qualitative heuristic approach was used to combine data layers for slope, vegetation, surficial geology unit, slope aspect, and permafrost distribution. ALD and RTS susceptibility maps were produced for present day permafrost distribution and also equilibrium permafrost distribution resulting from air temperature increases of 1–5 °C. The resulting susceptibility maps indicate that with warming and reduced permafrost extent, there will be fewer zones of high susceptibility. The maps for warmer conditions give a “snapshot” of a potential decrease in zones of high landslide susceptibility, but they do not show the potential landslide occurrence as permafrost warms and thaws. It is expected that as permafrost warms and thaws, ALD and RTS activity will increase until conditions stabilize as permafrost disappears.