Deformation Characteristics and Mechanisms of a Large Landslide at the Northeastern Margin of the Tibetan Plateau Based on Multi-source Data Integration: A Case Study of the Lade–Lijiaxia Landslide, Qinghai Province, China

Under the combined effects of Tibetan Plateau uplift and global climate warming, the transition zone between the northeastern Tibetan Plateau and the Loess Plateau has become one of the most landslide-prone regions worldwide. Intense tectonics, abundant material supply, and densely developed faults produce landslides with large volumes, multi-stage evolution, and complex failure mechanisms, posing severe threats to infrastructure and human safety. However, progressive deformation processes and multi-scale controls remain poorly understood.

This study investigates the Lade–Lijiaxia landslide using an integrated “space–air–ground–subsurface” framework. Field investigations, systematic mapping of cracks and rupture surfaces, high-resolution remote sensing, SBAS-InSAR monitoring (140 SAR images), XRD mineralogical analysis, and SEM observations are combined to elucidate the landslide’s structural features, time-dependent deformation, and material basis.

Results indicate: (1) The landslide’s spatial distribution, boundaries, and internal structure are strongly controlled by regional tectonics. It develops along tectonically weakened zones, with the main sliding direction aligned with dominant lineaments. The landslide comprises a distinct sliding block and a creeping block (~1.5 × 10⁸ m³), representing a tectonically controlled progressive failure mode; (2) Crack and rupture surface analysis shows dominant crack orientations of ~30° and 125°, and rupture dip directions of 130°, 310°, and 20°, reflecting rear scarp tension, internal creep, and sliding surface geometry; (3) SBAS-InSAR indicates slow deformation, with the creeping block reaching ~170 mm/yr, accelerating seasonally during summer–autumn and warm spring due to rainfall and freeze–thaw cycles; (4) XRD reveals vertical heterogeneity: clay content is ~22% in the upper Quaternary deposits and ~38% in underlying Miocene mudstone, dominated by illite. SEM shows localized clay enrichment, fragmented microstructures, and well-developed pores, providing microstructural evidence for long-term creep and strength reduction.

Overall, long-term deformation is primarily controlled by deep-seated tectonics and lithology, while shallow deformation is triggered by seasonal hydrothermal processes. These results improve understanding of progressive failure and creep evolution of large landslides at the northeastern Tibetan Plateau margin and provide insights for hazard assessment and long-term monitoring in the plateau–loess transition zone.

Map of Location Study Area

Geological Map of Study Area