Spatial pattern and driving mechanisms of geohazards in the lower yarlung zangbo suture zone: implications for engineering construction in extreme mountainous environments

The lower Yarlung Zangbo Suture Zone represents an extreme geohazard environment driven by intense tectonic activity and monsoonal hydrology. This study established a database of 492 hazard points (2013–2022) and developed a PCA-LR hybrid model to address multicollinearity and subjectivity in susceptibility assessment. Principal Component Analysis (PCA) was used for dimensionality reduction, followed by Logistic Regression (LR) for sensitivity-based weight refinement.Results reveal significant spatial clustering. Notably, 29.5% of hazards occur on gentle valley slopes (0°–13°), identifying these as accumulation zones for high-altitude long-runout events. Although slope aspect showed low variance in PCA, it demonstrated high sensitivity in the LR model; hazard density on windward slopes is 2.3 times higher than on leeward slopes, highlighting critical microclimatic effects. Furthermore, 83% of hazards cluster within 1,000 m of road networks due to the coupling of unloading fractures and fluvial erosion. The model achieved robust predictive performance (mean AUC = 0.87 ± 0.03 under 5-fold spatial cross-validation). We recommend “avoidance-first” strategies, such as substituting roads with tunnels in highly sensitive segments, to ensure the long-term stability of strategic infrastructure in this extreme mountainous environment.