Solifluction processes in the Arctic are highly complex, introducing uncertainties in estimating current and future soil carbon storage and fluxes, and assessment of hillslope and infrastructure stability. This study aims to enhance our understanding of triggers and drivers of soil movement of permafrost-affected hillslopes in the Arctic. To achieve this, we established an extensive soil deformation and temperature sensor network, covering 48 locations across multiple hillslopes within a 1 km² watershed on the Seward Peninsula, AK. We report depth-resolved measurements down to 1.8 m depth for May to September 2022, a period conducive to soil movement due to deepening thaw layers and frequent rain events. Over this period, surface movements of up to 334 mm were recorded. In general, these movements occur close to the thawing front, and are initiated as thawing reaches depths of 0.4–0.75 m. The largest movements were observed at the top of the south-east facing slope, where soil temperatures are cold (mean annual soil temperatures averaging −1.13 °C) and slopes are steeper than 15°. Our analysis highlights three primary factors influencing movements: slope angle, soil thermal conditions, and thaw depth. The latter two significantly impact the generation of pore water pressures at the thaw–freeze interface. Specifically, soil thermal conditions govern the liquid water content, while thaw depth influences both the height of the water column and, consequently, the pressure at the thawing front. These factors affect soil properties, such as cohesion and internal friction angle, which are crucial determinants of slope stability. This underscores the significance of a precise understanding of subsurface thermal conditions, including spatial and temporal variability in soil temperature and thaw depth, when assessing and predicting slope instabilities. Based on our observations, we developed a factor of safety proxy that consistently falls below the triggering threshold for all probes exhibiting displacements exceeding 50 mm. This study offers novel insights into patterns and triggers of hillslope movements in the Arctic and provides a venue to evaluate their impact on soil redistribution.

中文翻译：

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使用邻近山坡的密集监测方法深入了解温暖的永久冻土北极景观中的季节性泥流过程

北极的泥流过程非常复杂，给当前和未来土壤碳储存和通量的估计以及山坡和基础设施稳定性的评估带来了不确定性。这项研究旨在加深我们对北极受永久冻土影响的山坡土壤运动的触发因素和驱动因素的了解。为了实现这一目标，我们建立了广泛的土壤变形和温度传感器网络，覆盖阿拉斯加州苏厄德半岛1 km ²流域内多个山坡上的 48 个位置。我们报告了 2022 年 5 月至 9 月深度可达 1.8 m 的深度分辨测量结果，这一时期由于融层加深和频繁的降雨事件而有利于土壤移动。在此期间，记录到的表面移动量高达 334 毫米。一般来说，这些运动发生在解冻前沿附近，并在解冻深度达到 0.4-0.75 m 时开始。最大的运动发生在东南向斜坡的顶部，那里的土壤温度较低（年平均土壤温度为-1.13°C），斜坡陡度超过15°。我们的分析强调了影响运动的三个主要因素：坡度角度、土壤热条件和解冻深度。后两者显着影响解冻-冻结界面孔隙水压力的产生。具体来说，土壤热条件控制液态水含量，而解冻深度影响水柱的高度，从而影响解冻前沿的压力。这些因素影响土壤特性，例如粘聚力和内摩擦角，它们是边坡稳定性的关键决定因素。这强调了在评估和预测边坡不稳定性时精确了解地下热条件（包括土壤温度和解冻深度的空间和时间变化）的重要性。根据我们的观察，我们开发了一个安全系数代理，对于所有位移超过 50 毫米的探头，该安全系数始终低于触发阈值。这项研究为北极山坡运动的模式和触发因素提供了新颖的见解，并提供了评估其对土壤重新分布影响的场所。