Catastrophic Rock-Slope Failures in NW Scotland: Quantitative Analysis and Implications
Catastrophic Rock-Slope Failures in NW Scotland: Quantitative Analysis and Implications
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苏格兰西北部的灾难性岩坡破坏：定量分析和影响
DOI：
10.1080/14702541.2016.1156148
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发表时间：
2016
影响因子：
1
通讯作者：
C. Ballantyne
中科院分区：
文献类型：
--
作者：
James A.S. Cave;C. Ballantyne
利用谷歌Earth™图像，在苏格兰西北部lewis片麻岩（LG）、Torridon砂岩（TS）、寒武纪石英岩（CQ）和Moine片岩（MS）地形上识别了126个冰期后灾难性岩坡破坏（prsf）和66个无碎屑破坏陡坡（DFFSs）。对这些数据的面积和坡度进行归一化处理表明，≥25°斜坡上的RSF密度在MS > LG≈CQ > TS序列中减小。大多数与构造明显不一致，表明沿坡（次）平行节理的破坏比沿顺层或片理面破坏更为常见。dffs代表失效疤痕，其中跳动的碎片已被后来的冰川除去。在洛蒙德·里德万斯湖（Loch Lomond Readvance）的界限之外记录了18个，这意味着它们在最后一次冰盖冰川时期幸存下来，并支持了这样一种观点，即许多陡峭的上层岩石斜坡是由重力驱动的岩石分离而不是冰川侵蚀所主导的。我们认为，由于记录到的74%的prsf和dfs位于坡峰或其附近，许多RSFs可能是由地壳反弹引起的断层（再）激活引起的冰川地震引发的。44%的记录prsf和dfs发生在旋回中，这表明在连续的冰期-间冰期旋回中旋回的扩大涉及冰川侵蚀的加深、岩石-斜坡破坏的顶壁退缩以及随后的冰川作用中RSF碎屑的移除。
ABSTRACT 126 postglacial catastrophic rock-slope failures (PRSFs) and 66 debris-free failure scarps (DFFSs) were identified using Google Earth™ imagery on Lewisian Gneiss (LG), Torridon Sandstone (TS), Cambrian Quartzite (CQ) and Moine Schist (MS) terrains in NW Scotland. Normalisation of these data for area and gradient shows that RSF density on slopes ≥25° decreases in the sequence MS > LG ≈ CQ > TS. Most are apparently discordant with structure, suggesting that failure along slope-(sub)parallel joints was more common than failure along bedding or foliation planes. DFFSs represent failure scars from which runout debris has been removed by later glaciation. Eighteen were recorded outside the limits of the Loch Lomond Readvance, implying that they survived the last ice-sheet glaciation, and support the view that many steep upper rock slopes have been dominated by gravity-driven rock detachment rather than glacial erosion. We argue that many RSFs were probably triggered by Lateglacial earthquakes due to fault (re)activation by crustal rebound, as 74% of recorded PRSFs and DFFSs are located at or near slope crests. 44% of recorded PRSFs and DFFSs occur in cirques, suggesting that cirque enlargement during successive glacial-interglacial cycles involved deepening by glacial erosion, headwall retreat by rock-slope failure and removal of RSF debris during subsequent glaciation.