In 2018, Baige, Tibet, witnessed two consecutive large-scale landslides, causing significant damage and drawing widespread attention. From March 2011 to February 2018, the Baige landslide exhibited a 50-meter displacement without complete failure, culminating in a collapse in October 2018. The mechanisms behind its resistance to failure despite substantial deformation and the influence of the complex geo-structure within the tectonic mélange belt remain unclear. To address these questions, this study utilized a multidisciplinary approach, integrating on-site geological field mapping, surface deformation monitoring, multielectrode resistivity method, and deep displacement analysis. The aim was to evaluate the impact of the intricate geo-structure within the tectonic mélange belt on the Baige landslide events. Findings reveal that the landslide’s geo-structure consists of structurally fractured, mesh-like rock masses, including heterogeneous lenticular rock masses and intermittent brittle shear zones distributed around the lens-shaped rock masses. The study underscores that the inhomogeneous and weakly deformed lenticular rock masses function as natural locked segments, governing the stability of the Baige landslide. Specifically, the relatively intact and hard granodiorite porphyry play a crucial role in locking the landslide’s deformation. Deep displacement analysis indicates that the brittle shear zones act as the sliding surfaces. The progressive destruction of the locked segments and the gradual penetration of brittle shear zones, driven by gravitational potential energy, contribute to the landslide occurrence. This research provides critical insights into the formation mechanisms of large-scale landslides within tectonic mélange belts.
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