Pre- and post-failure spatiotemporal evolution of loess landslides: a case study of the Jiangou landslide in Ledu, China

Information about the long-term spatiotemporal evolution of landslides can improve our understanding of the landslide development process and can help prevent landslide disasters. However, few studies have been devoted to the pre- and post-failure spatiotemporal evolution process and pattern of landslides. Therefore, we studied the pre- and post-failure geomorphic changes and spatiotemporal evolution of the 2019 Jiangou landslide based on field investigations, interferometric synthetic aperture radar (InSAR), unmanned aerial vehicle (UAV) observations, and remote sensing techniques. The results show that the volume of the deposition of the Jiangou landslide is less than the depletion volume, which means the remaining landslide materials were washed away when the dammed lake collapsed. Moreover, the InSAR technique has an advantage in terms of the retrieval of pre- and post-failure creep deformation. Our analysis suggests that the Jiangou landslide has experienced long-term creep. Potential landslide risks still exist after the previous failure event. Furthermore, we found that the pre- and post-failure spatiotemporal deformation processes and evolutionary patterns of the landslide are different. The pre-failure evolutionary pattern of the landslide is a progressive failure mode, while the post-failure evolutionary pattern is a retrogressive failure mode. This evolution provides a reference for local governments to further monitor or take effective prevention measures against future landslide failures.