Topographic and Ground‐Ice Controls on Shallow Landsliding in Thawing Arctic Permafrost

H T Mithan,P J Cleall,T C Hales

doi:10.1029/2020gl092264

H T Mithan, P J Cleall + Show 1 more

Open Access

https://doi.org/10.1029/2020gl092264

Copy DOI

Abstract

AbstractAn increase in Arctic shallow landsliding is a potential consequence of climate warming. Warmer summer‐air temperatures and larger rainfall events drive heat into the active layer, melting ice and decreasing soil shear stress. Topography has the potential to exacerbate landsliding by controlling the distribution of ground ice and the movement of water in the subsurface. We demonstrate that shallow Arctic landslides initiate in zero‐order drainage basins consistent with models of shallow landsliding in non‐permafrost environments. However, the low average slopes and low concavity of Arctic hillslopes cannot create pore‐water pressures high enough to generate landsliding. Instead, two‐dimensional slope stability modeling suggests that the vertical distribution of ground‐ice distributions controls landslide susceptibility. High ground‐ice concentrations close to the potential failure plane act as a stronger control than high average ice volumes or rapid thawing. Our results demonstrate that landslide susceptibility is strongly affected by topographic controls on ground ice and hydrology.

Highlights

Exceptional weather events are becoming more frequent in the Arctic causing permafrost to thaw rapidly (Dobricic et al, 2020; Lewkowicz & Way, 2019)
active-layer detachment (ALD) failures form within convergent topography in the uppermost parts of catchments
With studies indicating that regions of convergent topography have higher ground ice content (Balser, 2015; Trochim, Prakash et al, 2016) we developed a series of tests to better understand how melting ground ice can trigger ALD failure

Summary

Introduction

Exceptional weather events are becoming more frequent in the Arctic causing permafrost to thaw rapidly (Dobricic et al, 2020; Lewkowicz & Way, 2019). Melting ice in thawing permafrost increases pore-water pressures within the active layer that destabilize the overlying soil causing retrogressive thaw slumps (Balser et al, 2014; Lewkowicz & Way, 2019), solifluction (Harris et al, 2011), and active-layer detachment (ALD) failures (Lewkowicz, 1990) When these mass-wasting processes occur in proximity to populated areas they damage infrastructure (Hanna et al, 1998), cause economic loss (Allard et al, 2012), and threaten public safety (Larsson, 1982). A better understanding of the processes controlling hillslope instabilities will help quantify the contribution of mass-wasting processes to Arctic greenhouse gas emissions and evaluate their threat to infrastructure and public safety

Methods

Results

Conclusion