Heifangtai loess landslide type and failure mode analysis with ascending and descending Spot-mode TerraSAR-X datasets

Abstract

The Heifangtai loess terrace in northwest China is a well-known area to study loess landslides because of its frequent occurrence, various types, and complex trigger factors. The determination of loess landslide type and failure mode is of great significance for the landslide risk assessment, hazard mitigation, and prevention. In this study, ascending and descending Spot-mode TerraSAR-X datasets are employed to analyze the deformation patterns and failure modes of loess landslides in Xinyuan landslide group, Heifangtai terrace, by using multidimensional small baseline subsets (MSBAS) technique. First, the locations of three active landslides are delineated by independent InSAR observations from both ascending and descending TerraSAR-X datasets. Then, two-dimensional deformation rates and time series results in both vertical and horizontal east-west directions of the identified landslides are calculated using MSBAS technique. Finally, the deformation types and failure modes of landslides in the study sites are analyzed by jointly using the two-dimensional deformation rates and time series results, topographic map, remote sensing images, and previous studies on the loess landslide failure modes. With the aid of complementary data including topographic map, remote sensing image, previous studies on the loess landslide failure modes, and field investigations, two-dimensional deformation results derived from ascending and descending SAR images are compatible with three typical failure modes of loess landslide including loess-bedrock planar slide, retrogressive failure, and loess slide. Furthermore, the two-dimensional deformation derived from InSAR technique can give much detailed deformation characteristics and movement of loess landslide.