Insights into the deformation kinematics of Xieliupo landslide, Zhouqu, China, through remote sensing and geomorphological observations.

The Xieliupo landslide is a typical large-scale active landslide in Zhouqu, China, in the Pingding-Huama fault zone that has slid eight times since the beginning of the twentieth century. The landslide has caused catastrophic environmental, economic, and life losses in the area. In this study, combining the geomorphological field surveys, Unmanned Aerial Vehicle (UAV) mapping, interpretation of optical images, InSAR, and Cosi-Corr (Co-registration of Optically Sensed Images and Correlation) monitoring analysis, we conducted insights into the deformation kinematics of large Xieliupo landslide. The Xieliupo landslide has the characteristics of graded sub-activity with eight secondary landslides. The secondary landslides I and II in the upper parts are loess slide-flow with a moving pattern of creep–rip–push on the condition of steep gradient and the triggering of intense precipitation. The middle part was divided into two sides by a relatively stable ridge, where the loess rotational landslides III and collapse VI in the northern side are controlled by low-lying terrain in the valley, and the landslides IV and V are moderately active under the influence of steep gradient and compression from the landslides I and II. The secondary landslides VII and VIII in the toe are relatively slightly active with a gentle slope gradient influenced by road construction and Bailong River erosion. Time-series InSAR deformation from 2015 to 2020 revealed a close positive correlation between accelerating displacements and increasing precipitation. The deformation response characteristics of cascade collapse retreat and fluctuating acceleration of the Xieliupo landslide to heavy rainfall were revealed. The seismic activity is one probable factor contributing to the reactivated displacement of Xieliupo landslide. Notably, the intense rainfall on August 13, 2020, triggered the maximum displacement of 5.93 m in a sliding direction of 319° (NW) at secondary landslide II. This study significantly provides new insight into the deformation characteristics and kinematics of Xieliupo and reference for catastrophic landslide hazard mitigation. The proposed technique strategy can be used for analyzing similar large complex landslides in other mountainous regions. [ABSTRACT FROM AUTHOR]