The impact of ground-ice thaw on landslide geomorphology and dynamics: two case studies in northern Iceland

Abstract

As consequence of ongoing climate change, permafrost degradation is thought to be increasingly affecting slope stability in periglacial environments. This is of growing concern in Iceland, where in the last decade, permafrost degradation has been identified among the triggering factors of landslides. The role of ground ice in conditioning the morphology and dynamics of landslides involving loose deposits is poorly understood. We show the geomorphological impact of the Móafellshyrna and Árnesfjall landslides that recently occurred in ice-cemented talus deposits in northern Iceland. Using field and aerial remote-sensing measurements of the morphological and morphometric characteristics of the landslides, we assess the influence of thawing ground ice on their propagation style and dynamics. The two mass movements are complex and are similar to rock- and debris-ice avalanches, changing trajectory and exhibiting evidence of transitioning their style of motion from a dry granular mass to a debris flow-like movement via multiple pulses. We infer that the thawing of ground ice together with the entrainment of saturated material provided the extra fluid causing this change in dynamics. The hazardous consequences of permafrost degradation will increasingly affect mountain regions in the future, and ground-ice thaw in steep terrain is a particularly hazardous phenomenon, as it may induce unexpected long-runout failures and can cause slope instability to continue even after the landslide event. Our study expands our knowledge of how landslides develop in unstable ice-cemented deposits and will aid assessment and mitigation of the hazard that they pose in Iceland and other mountainous periglacial areas.

Quantifying the effect of a retrogressive thaw slump on soil freeze–thaw erosion in permafrost regions on the Qinghai–Tibet Plateau, China

“…The ice‐rich permafrost distribution in the RTS development area may indicate a link to topography related to the massive ground ice ablation. Meanwhile, the ground ice ablation or the ice‐rich permafrost thaw mainly happened in the headwall (Luo et al, 2019; Morino et al, 2021). The geotemperature field can also present that the thawing depth of the ice‐rich permafrost in the headwall was more than in the undisturbed terrain due to the massive ground ice exposed directly to the air.…”

Experimental study of sediment transport processes by liquid water and brine under Martian pressure

“…A hillshaded relief image for each DTM was produced using ArcGIS (version 10.4). The difference between the values of the DTMs after and before (DTM of difference -DoD, e.g., Herny et al, 2019;Morino et al, 2019Morino et al, , 2021Williams, 2012;Raack et al, 2017) was computed in order to visualise the erosion zones (negative values) and the deposition zones (positive values), and to calculate the volume of sediment moved during each experiment (DoDs available in Supplementary Files). We observed four different sediment transport processes: overland flow (the liquid flowing at the surface of the sand bed, carrying sediment); percolation (the liquid infiltrating within the sand bed around the point of liquid supply); boiling (the liquid changing to gas phase on the sand bed, leading to grain ejection; Massé et al, 2016); and "levitation" (liquid-saturated pellets of sand and changing to the gas phase, leading to these pellets to move downslope quickly, supported by cushions of water vapour; Raack et al, 2017).…”

Denudation and geomorphic change in the Anthropocene; a global overview.

“…For example, in cold climate environments, contemporary climate change is a major driver of increased denudation, e.g. through glacier retreat and permafrost degradation (Zwoliński, 2007;Costa et al, 2018;Li et al, 2020;Morino et al, 2021).…”