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.

由于持续的气候变化，多年冻土的退化被认为正日益影响冰缘环境中的边坡稳定性。这在冰岛引起了越来越多的关注，在过去的十年中，冰岛已将多年冻土退化确定为滑坡的触发因素之一。人们对地下冰在调节涉及松散沉积物的滑坡的形态和动力学方面的作用了解甚少。我们显示了最近发生在冰岛北部冰水泥距骨矿床中的Móafellshyrna和Árnesfjall滑坡的地貌影响。通过对滑坡的形态和形态特征进行现场和空中遥感测量，我们评估了融化的地面冰对其传播方式和动力学的影响。这两个质量运动很复杂，类似于岩石和碎片冰雪崩，它们的轨迹不断变化，并显示出它们的运动方式已通过多个脉冲从干燥的颗粒状运动转变为类似泥石流的运动。我们推断，地面冰的融化以及饱和物质的夹带提供了额外的流体，从而引起了动力学上的这种变化。多年冻土退化的危险后果将在未来越来越多地影响山区，并且在陡峭地形中的冰融解是一种特别危险的现象，因为它可能引发意想不到的长期跳动破坏，甚至在发生滑坡事件后仍会导致边坡不稳定。 。