Ongoing Landslide Deformation in Thawing Permafrost

Thawing permafrost influences landslide initiation, but observation of landslide development in thawing permafrost is limited. To evaluate the impact of landslide age, morphology, and permafrost conditions, we quantified topographic deformation of three shallow-angle, thaw-initiated landslides in discontinuous permafrost in Alaska. Two of the landslides initiated <3 years ago and the third initiated 20-50 years ago. The two recent landslides are still mobile, with maximum elevation loss of 0.8 +/- 0.04 and 1.0 +/- 0.08 m over the study period. At one site, shallow permafrost (<2.3 m) is present at 0.4-1.9 m depth adjacent to the landslide but not within the landslide. The lack of shallow permafrost within the slide indicates that permafrost has thawed faster within the landslide because ground surface disturbance increased heat flux to the subsurface. We propose that a positive feedback between permafrost thaw and landslide development exists. Climate warming will accelerate loss of permafrost in recent landslides.