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TitleThe role of massive ice and exposed headwall properties on retrogressive thaw slump activity
AuthorHayes, S; Lim, M; Whalen, DORCID logo; Mann, P J; Fraser, P; Penlington, R; Martin, J
SourceJournal of Geophysical Research, Earth Surface e2022JF006602, 2022 p. 1-16, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20220366
PublisherJohn Wiley and Sons Inc
Mediapaper; digital; on-line
File formatpdf
ProvinceNorthwest Territories
AreaPelly Island; Beaufort Sea; Tuktoyaktuk Peninsula
Lat/Long WENS-133.1431 -133.1167 69.4167 69.4000
SubjectsScience and Technology; Nature and Environment; general geology; slumps; massive ice; permafrost; Geomorphology
Illustrationsphotographs; diagrams; location maps; satellite imagery; tables; graphs
ProgramClimate Change Geoscience Coastal Infrastructure
Released2022 11 01
Retrogressive Thaw Slumps (RTSs), a highly dynamic form of mass wasting, are accelerating geomorphic change across ice-cored permafrost terrain, yet the main controls on their activity are poorly constrained. Questions over the spatial variability of environmentally sensitive buried massive ice (MI) bodies and a paucity of high-spatial and temporal resolution topographic data have limited our ability to project their development and wider impacts. This research addresses these key problems by investigating RTS processes on Peninsula Point — the type site for intra-sedimental MI in the Western Canadian Arctic. Utilizing high-resolution topographic data from drone surveys in 2016, 2017 and 2018 we (1) measure the temporal and spatial variations in exposed headwall constituents and retreat rates, (2) determine the spatial pattern of subsurface layering using passive seismic monitoring and (3) combine these to analyse and contextualise the factors controlling headwall retreat rates. We find that headwall constituents, namely MI and overburden thickness, act as significant controls over rates of headwall retreat. Where a persistent ice exposure is present and overburden thickness remains < 4 m, headwall retreat is typically over twice as where overburden is > 4 m and ice is absent inland of the headwall. Furthermore, the combination of the passive seismic and photogrammetric data allows for the creation of a 3D site model, highlighting the variability in internal layering and demonstrating the limitations of simple extrapolations based on headwall exposures. By combining detailed analysis of headwall retreat with exposures of MI, overburden and the internal layering, more accurate predictions of headwall retreat rates are possible. These results provide fresh insights into the controls on headwall retreat rates and new approaches to improve the predictability of these rates.
Summary(Plain Language Summary, not published)
Retrogressive thaw slumps (thaw slumps) are a form of landslide that occurs when thick layers of ice under the ground are exposed and thaw, creating muddy flows that can grow to cover thousands of m2 in just a few years. These processes are occurring more frequently in the western Canadian Arctic during the last two decades, becoming one of the primary causes of landscape change. This research examines how variation in the ice and overburden thickness of the thaw slump headwalls (a prominent, near vertical cliff at the back of a thaw slump), affects their rate of growth. We find that a persistent layer of ice, and a thin soil overburden, tends to promote headwall retreat rates much faster than otherwise. We also use naturally occurring seismic vibrations to map the buried ice and show how it varies inland, and then use this information to improve predictions of how fast the headwall will retreat. This research suggests that detailed knowledge of how the internal ice and overburden layering varies is critical to understanding how thaw slumps evolve and to predict their development.

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