University of Innsbruck, Department of Geology, Innsbruck, Austria.
Central Institute for Meteorology and Geodynamics, Vienna, Austria.
Nat Commun. 2021 Feb 16;12(1):1059. doi: 10.1038/s41467-021-21327-9.
Large prehistoric rockslides tend to occur within spatio-temporal clusters suggesting a common trigger such as earthquake shaking or enhanced wet periods. Yet, trigger assessment remains equivocal due to the lack of conclusive observational evidence. Here, we use high-resolution lacustrine paleoseismology to evaluate the relation between past seismicity and a spatio-temporal cluster of large prehistoric rockslides in the Eastern Alps. Temporal and spatial coincidence of paleoseismic evidence with multiple rockslides at ~4.1 and ~3.0 ka BP reveals that severe earthquakes (local magnitude M 5.5-6.5; epicentral intensity I VIII¼-X¾) have triggered these rockslides. A series of preceding severe earthquakes is likely to have progressively weakened these rock slopes towards critical state. These findings elucidate the role of seismicity in preparing and triggering large prehistoric rockslides in the European Alps, where rockslides and earthquakes typically occur in clusters. Such integration of multiple datasets in other formerly glaciated regions with low to moderate seismicity will improve our understanding of catastrophic rockslide drivers.
大型史前岩崩往往在时空集群中发生，这表明存在共同的触发因素，如地震震动或增强的湿润期。然而，由于缺乏确凿的观测证据，触发因素的评估仍然存在争议。在这里，我们使用高分辨率湖泊古地震学来评估过去的地震活动与阿尔卑斯山东部一个大型史前岩崩时空集群之间的关系。古地震证据与4.1 和3.0 ka BP 多处岩崩的时空巧合表明，剧烈地震（震级 ML5.5-6.5；震中烈度 VIII¼-X¾）触发了这些岩崩。一系列先前的剧烈地震可能使这些岩坡逐渐向临界状态减弱。这些发现阐明了地震活动在为欧洲阿尔卑斯山的大型史前岩崩做准备和触发方面的作用，在那里，岩崩和地震通常集群发生。在地震活动低至中等的其他曾有冰川作用的地区，将多个数据集进行这种整合将提高我们对灾难性岩崩驱动因素的理解。
