The hazardous impact and erosive potential of slow‐moving landslides depends on landslide properties including velocity, size, and frequency of occurrence. However, constraints on size, in particular, subsurface geometry, are lacking because these types of landslides rarely fully evacuate material to create measurable hillslope scars. Here, we use pixel offset tracking with data from the NASA/JPL Uninhabited Aerial Vehicle Synthetic Aperture Radar to measure the three‐dimensional surface deformation of 134 slow‐moving landslides in the northern California Coast Ranges. We apply volume conservation to infer the actively deforming thickness, volume, geometric scaling, and frictional strength of each landslide. These landslides move at average rates between ∼0.1–2 m/yr and have active areas of ∼6.10 × 10³–2.35 × 10⁶ m², inferred mean thicknesses of ∼1.1–25 m, and volumes of ∼7.01 × 10³–9.75 × 10⁶ m³. The best fit volume‐area geometric scaling exponent is γ ∼ 1.2–1.5, indicating that these landslides fall between typical soil and bedrock landslide scaling. A rollover in the scaling relationship suggests that the largest landslide complexes in our data set become large primarily by increasing in area rather than thickness. In addition, the slow‐moving landslides display scale‐dependent frictional strength, such that large landslide tend to be weaker than small landslides. This decrease in frictional strength with landslide size is likely because larger landslides are composed of higher proportions of weak material. Our work shows how state of the art remote sensing techniques can be used to better understand landslide processes and quantify their contribution to landscape evolution and hazards to human safety.

中文翻译：

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利用NASA / JPL UAVSAR的3D速度测量推论慢速滑坡的地下几何形状和强度

缓慢移动的滑坡的危险影响和潜在侵蚀取决于滑坡的性质，包括速度，大小和发生频率。然而，由于这些类型的滑坡很少完全疏散物质以产生可测量的山坡疤痕，因此缺乏对尺寸的限制，尤其是对地下几何形状的限制。在这里，我们将像素偏移跟踪与来自NASA / JPL无人飞行器合成孔径雷达的数据一起使用，以测量北加州海岸地区134个缓慢移动的滑坡的三维表面变形。我们应用体积守恒来推断每个滑坡的主动变形厚度，体积，几何比例和摩擦强度。这些滑坡的平均移动速度约为0.1-2 m / yr，活动面积约为6.10×10 ^3。–2.35×10 ⁶  m ²，推断平均厚度为〜1.1–25 m，体积为〜7.01×10 ³ –9.75×10 ⁶  m ³。最佳拟合体积区域几何比例指数为γ约为1.2–1.5，表明这些滑坡介于典型的土壤滑坡和基岩滑坡之间。比例关系的翻转表明，我们数据集中最大的滑坡综合体主要是通过增加面积而不是增加厚度而变大。此外，缓慢移动的滑坡表现出与尺度有关的摩擦强度，因此大滑坡往往比小滑坡弱。摩擦强度随滑坡尺寸的减小而降低的原因很可能是因为较大的滑坡由较高比例的薄弱材料组成。我们的工作表明如何使用先进的遥感技术更好地了解滑坡过程，并量化其对景观演变和对人类安全的危害的贡献。