ABSTRACT Rockfalls are a major aspect concerning morphodynamics in high mountain areas and represent a serious hazard for people and infrastructure. Recently, an increase of rockfall activity has been observed which is probably related to the destabilization of rock slopes through climate-related changes of the mountain cryosphere. This study investigates the rockfall distribution during a 4-year monitoring period by systematic observation with bi-temporal Airborne Laser Scanning DTMs in an area of 610.7 km² in the Ötztal Alps/Tyrol, Austria. The analyses of the 93 detected rockfall events indicate that rockfall activity is highest in proglacial areas. Further 83.9% of all rockfall source areas were mapped in bedrock where the modelled mean annual ground temperature (MAGT) indicates perennial frozen conditions. The results demonstrate the importance of thermal effects on the destabilization of rock faces and show that the triggering of rockfalls is closely related to changes in the glacier and permafrost regime. 18 low-magnitude rockfalls with volumes between 69 ± 3 m³ and 8420 ± 89 m³ are examined in detail. On the base of the analysis of these events energy line angles of 28.7° for the Fahrböschung and 19.9° for the minimum shadow angle can be derived and significantly longer runout distances on glaciated rockfall paths are observed.

中文翻译：

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高山落石动力学：冰冻圈变化下落石活动与跳动评估

摘要 落石是高山地区形态动力学的一个主要方面，对人员和基础设施构成严重危害。最近，观察到落石活动增加，这可能与山区冰冻圈气候相关变化导致岩坡不稳定有关。本研究通过在奥地利奥茨塔尔阿尔卑斯山/蒂罗尔州 610.7 平方公里的区域内使用双时相机载激光扫描 DTM 进行系统观察，调查了 4 年监测期间的落石分布。对检测到的 93 起落石事件的分析表明，落石活动在前冰期地区最高。此外，83.9% 的落石源区域绘制在基岩中，其中模拟的年平均地温 (MAGT) 表明常年冰冻条件。结果证明了热效应对岩面不稳定的重要性，并表明落石的触发与冰川和永久冻土区的变化密切相关。详细检查了 18 个体积在 69 ± 3 m³ 和 8420 ± 89 m³ 之间的低级落石。根据对这些事件的分析，Fahrböschung 的能量线角度为 28.7°，最小阴影角度为 19.9°，并且观察到冰川落石路径上明显更长的跳动距离。