Landslides occur in a variety of forms that are a function of climactic setting, tectonic setting, geomorphic and geologic setting, and the shear strength of soil and rock. While major advances in characterizing the spatial influence of these settings on landslide activity have occurred in recent years, there has been limited progress on understanding spatial trends in shear strength properties and their influence on landslide activity. Herein, we propose a regional‐scale forensic methodology to establish first‐order estimates of landslide shear strength. This approach is performed using (1) interpolation of rupture surface geometry and (2) three‐dimensional slope stability analysis. Thereafter, distributions of back‐analyzed shear strengths of landslide inventories are used to demonstrate that distinctly different trends are observed when comparing geologic units and landslide type. It is shown that there is generally an inverse correlation between landslide volume and friction angle, suggesting that larger earthflows tend to be in a residual state of shear, while smaller deep‐seated failures tend to occur in stronger, possibly cemented materials. Significant uncertainty lies in characterization of hydrological conditions; nonetheless, upper and lower bounds of groundwater conditions still reflect significant differences in inferred regional trends in shear strength properties between geologic settings. A comparison of three‐dimensional forensic back analyses to conventional, infinite slope conditions often used in susceptibility analyses suggests that conventional approaches may significantly overestimate landslide shear strengths at a regional scale.

中文翻译：

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通过滑坡量清单的三维反分析推断抗剪强度特性的地质趋势

滑坡以各种形式发生，这是高海拔环境，构造环境，地貌和地质环境以及土壤和岩石的抗剪强度的函数。尽管近年来在表征这些环境对滑坡活动的空间影响方面取得了重大进展，但在理解抗剪强度特性的空间趋势及其对滑坡活动的影响方面的进展有限。在此，我们提出了一种区域规模的法证方法，以建立滑坡抗剪强度的一阶估算。使用（1）破裂表面几何形状的插值和（2）三维边坡稳定性分析来执行此方法。之后，通过对滑坡清单进行反分析的抗剪强度分布，可以证明在比较地质单位和滑坡类型时观察到了截然不同的趋势。结果表明，滑坡体积与摩擦角之间通常呈反比关系，这表明较大的土流倾向于处于残余剪切状态，而较小的深部破坏往往发生在强度较高，可能是胶结的材料中。不确定性在于水文条件的特征。但是，地下水条件的上下边界仍然反映了地质环境之间的剪切强度特性推断区域趋势的显着差异。三维取证分析与常规分析的比较