Objectives Large deep-seated landslides are widely distributed in the alpine canyons of the Jinsha River in the eastern Tibetan Plateau, where complex terrain, geological conditions, and intense tectonic activity jointly control landslide formation and evolution. These landslides commonly exhibit multi-layered structures, multi-stage deformation, and superimposed failure processes, posing significant challenges for geological hazard investigation and risk mitigation. Accurate identification of the spatial structural characteristics and the deep sliding zones of large deep-seated landslides in alpine canyone areas remains a key and difficult issue. In the Diwu town of Batang County along the Jinsha River, a series of large deep-seated landslides have developed, among which the Diwuxiang landslide exhibits intense deformation, necessitating the relocation of the village. However, the deep structural configuration and geometry of sliding zones of this landslide have not yet been clearly revealed. This paper aims to systematically characterize the spatial structure of the Diwuxiang landslide and to explore an effective integrated geophysical investigation framework for large deep-seated landslides in alpine canyon regions.

Methods To further investigate the spatial structural characteristics of large deep-seated landslides in this region, an integrated approach combining field surveys, remote sensing interpretation, LiDAR (light detection and ranging) aerial surveys, high-density electrical resistivity tomography, and microtremor survey method (MSM). The spatial development characteristics of the Diwuxiang landslide are employed interpreted through the combined analysis of these methods.

Results The results indicate that the surface deformation of the Diwuxiang landslide is intense, characterized by widespread tensile cracks, damaged retaining walls and steep scraps. A total of 152 secondary landslides are identified within the landslide area, indicating strong internal deformation and fragmentation. High-density electrical resistivity tomography reveals that the Diwuxiang landslide generally exhibits low resistivity, with some localized areas displaying high resistivity. The MSM indicate that the stratigraphy of the landslide can be divided into a shallow cover layer (150-550 m/s), a medium-strongly weathered bedrock layer (430-840 m/s), and a weakly to unweathered bedrock layer (630-930 m/s). Combining the results from the two geophysical methods, it is concluded that the Diwuxiang landslide develops 2-3 sliding zones, with significant variability in resistivity at these locations, generally displaying low resistivity values of 100-150 Ω·m. The maximum depth of the sliding zones can reach up to 70 meters. The results obtained from the two geophysical methods are in good agreement, with the relative error in the revealed thickness of the sliding body being within 10%.

Conclusions The integrated application of high-density electrical resistivity tomography and microtremor survey methods effectively reveals the spatial structural characteristics and deep sliding zones of large deep-seated landslides in alpine canyon areas. Based on the established geophysical response-based investigation workflow provides a reliable and efficient technical approach for detecting the spatial structure of large deep-seated landslides in alpine canyon areas and offering important guidance for geological hazard assessment, monitoring, and disaster prevention in alpine canyon areas.