We conducted repeated successive passive seismic surveys on the La Praz unstable rock slope (∼13,000–15,000 m, Savoie, France), spanning over more than ten years. The last survey was conducted two months before its complete collapse in August 2023. We used the amplitude of Horizontal to Vertical Spectral Ratio at peak () to discriminate stable from unstable areas and delineate the fractures with major mechanical decoupling effect. We also classified the compartments in terms of rockfall hazard: the most prone-to-fall areas showed the highest (in the range [26–157]), compared to [7.5–19] on intermediate areas and 2.7 on adjacent stable rock mass.

中文翻译：

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利用被动地震绘制落石灾害图并检测岩石斜坡的先兆损害：拉普拉兹案例研究的经验教训


我们对拉普拉兹不稳定岩石边坡（~13,000-15,000 m，法国萨瓦省）进行了十多年的连续被动地震勘探。最后一次调查是在 2023 年 8 月其完全倒塌前两个月进行的。我们使用峰值 () 处的水平与垂直谱比的幅度来区分稳定区域和不稳定区域，并描绘具有主要机械解耦效应的裂缝。我们还根据落石危险对分区进行了分类：最容易发生落石的区域显示最高（范围为 [26-157]），而中间区域为 [7.5-19]，相邻稳定岩体为 2.7 。