ABSTRACT

Landslides are major geological hazards and frequently occur in mountainous areas with steep slopes, often causing significant loss. Interferometric Synthetic Aperture Radar (InSAR) has been widely used in landslide measurement over the last three decades. However, InSAR only can measure one-dimensional displacements (i.e. those in the radar’s line of sight (LOS) direction), resulting in the uncertainty between LOS displacement and the real slope displacement. In this paper, based on ascending and descending data from Sentinel-1 satellite, a wide-area potential landslide early identification was carried out using SBAS-InSAR in the whole of Mao County, a mountainous area in western Sichuan (China), with a total of 41 potential landslides successfully detected. Based on the quantitative analysis, the results show that the InSAR LOS measurement values are slope aspect and gradient-dependent. Finally, we innovatively derived a LOS displacement sensitivity map of InSAR in landslide measurement, revealing the relationship between LOS displacement, real displacements on slopes with arbitrary aspects and gradients, and SAR geometric distortion. This is a generalized finding useful for any slopes. It provides theoretical support to acquire and understand the real slope displacement from InSAR landslide measurement, which is vital to assist in correctly interpreting LOS displacement and carrying out subsequent quantitative geological engineering analysis.

摘要

滑坡是重大地质灾害，多发生在山坡陡峭的山区，往往造成重大损失。在过去的三十年里，干涉合成孔径雷达 (InSAR) 在滑坡测量中得到了广泛的应用。然而，InSAR 只能测量一维位移（即雷达视线（LOS）方向的位移），导致LOS 位移与真实斜坡位移之间存在不确定性。本文基于哨兵一号卫星的升降数据，利用SBAS-InSAR对川西山区茂县全域进行了大范围潜在滑坡早期识别，共成功检测到 41 处潜在滑坡。基于定量分析，结果表明，InSAR LOS 测量值是斜率方面和梯度相关的。最后，我们创新推导出了InSAR在滑坡测量中的LOS位移敏感性图，揭示了LOS位移与任意坡向和坡度斜坡上的实际位移与SAR几何畸变之间的关系。这是对任何斜率都有用的广义发现。为获取和理解InSAR滑坡测量中的真实边坡位移提供了理论支持，这对于辅助正确解释LOS位移和进行后续的定量地质工程分析至关重要。揭示了 LOS 位移、具有任意坡向和梯度的斜坡上的实际位移以及 SAR 几何失真之间的关系。这是对任何斜率都有用的广义发现。为获取和理解InSAR滑坡测量中的真实边坡位移提供了理论支持，这对于辅助正确解释LOS位移和进行后续的定量地质工程分析至关重要。揭示了 LOS 位移、具有任意坡向和梯度的斜坡上的实际位移以及 SAR 几何失真之间的关系。这是对任何斜率都有用的广义发现。为获取和理解InSAR滑坡测量中的真实边坡位移提供了理论支持，这对于辅助正确解释LOS位移和进行后续的定量地质工程分析至关重要。