Abstract The retreat of the Great Aletsch Glacier is accompanied by a series of slope failures in solid bedrock, which are heavily influenced by the presence of pre-existing deformation structures. Since the 1880’s, the Great Aletsch Glacier has shortened by more than 3 km and decreased about 400 m in thickness. As a reaction to the loss of the stabilizing effect of the ice, one of the largest active deep-seated landslides in the European Alps with an affected surface area of about 1.5 km2 called Moosfluh landslide is evolving. In this study, a multimethod approach combining field work, remote sensing techniques and microseismic monitoring is used to assess the effect of pre-existing structures on the landslide deformation processes. The landslide evolution from 2008 to 2018 could be reconstructed with high spatial resolution. Surface deformation analysis reveals the concentration of high deformation in narrow zones, allowing to directly link pre-existing tectonic and exhumation structures with landslide deformation processes. Toppling as the main gravity-driven process is enabled by reactivation of NE-SW striking, steeply SE dipping Alpine Handegg phase shear zones. Differences in the lateral detachment processes are attributed to shear zone bridges in the NE as well as fractures and shear zones similarly oriented to Alpine Oberaarb phase shear zones in the SW. At the landslide toe, a transition from toppling to sliding mechanism due to the formation of a continuous basal detachment surface can be observed, which is favored by the presence of exfoliation joints. The dramatic acceleration of the Moosfluh landslide in autumn 2016 is directly related to an increase in glacier height loss rate, which implies that glacier retreat is the main trigger of the landslide. A temporal stabilization of the landslide is recorded after 2017, most probably caused by the self-stabilizing properties of flexural toppling. However, microseismic data records a lateral propagation of the landslide, following the retreating Great Aletsch Glacier.

中文翻译：

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现有结构对 Moosfluh 滑坡及其横向传播的影响（瑞士大阿莱奇冰川）

摘要 大阿莱奇冰川的退缩伴随着固体基岩中的一系列斜坡破坏，这些破坏受预先存在的变形结构的影响很大。自 1880 年代以来，大阿莱奇冰川缩短了 3 公里以上，厚度减少了约 400 米。作为对冰的稳定作用丧失的反应，欧洲阿尔卑斯山最大的活动深层滑坡之一，其受影响的表面积约为 1.5 平方公里，称为 Moosfluh 滑坡。在这项研究中，结合实地工作、遥感技术和微地震监测的多方法方法用于评估预先存在的结构对滑坡变形过程的影响。2008-2018年滑坡演化可以用高空间分辨率重建。地表变形分析揭示了狭窄区域中高变形的集中，允许将预先存在的构造和折返结构与滑坡变形过程直接联系起来。通过重新激活 NE-SW 撞击、SE 陡倾的 Alpine Handegg 相剪切带，使倾覆成为主要的重力驱动过程。横向分离过程的差异归因于东北部的剪切带桥以及与西南部的高山 Oberaarb 相剪切带类似的断裂和剪切带。在滑坡趾部，可以观察到由于连续基底分离面的形成，从倾覆机制向滑动机制的转变，这有利于剥落节理的存在。2016 年秋季 Moosfluh 滑坡的急剧加速与冰川高度损失率的增加直接相关，这意味着冰川后退是滑坡的主要触发因素。2017 年之后记录到滑坡的时间稳定，很可能是由弯曲倾倒的自稳定特性引起的。然而，微震数据记录了大阿莱奇冰川后滑坡的横向传播。