Permafrost Detachment Slides: A Distinct High‐Magnitude Permafrost Mass Wasting Process

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Abstract
Warming permafrost is destabilizing landscapes, intensifying thaw‐driven mass wasting and giving rise to novel landslide forms. We characterize two recent (2017 and 2018), deep‐seated translational failures that we term Permafrost Detachment Slides (PDSs), which rapidly translocated 4.5 and 18 × 10 6 m 3 of frozen material into downstream environments. The PDS failure mechanism involves bottom‐up thaw, initiating gradual movement of the entire permafrost layer, producing distinct failure styles and deposits. Initial movement results in extensional cracks that increase water infiltration, accelerating thaw at depth and slope failure. We have identified hundreds of similar landslides in relatively thin (−1°C) permafrost of the Mackenzie Valley, NWT. Thermal modeling indicates fire‐induced effects can cause thawing at the permafrost base over decadal timescales. Though PDSs occur rapidly, their effects persist, as thermokarst processes alter ice‐rich scarps and deposits, mobilizing sediments, solutes, and carbon into downstream environments.
Funding Information
  • Natural Sciences and Engineering Research Council of Canada

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