Review of formation mechanisms and risk assessment of geohazard chains in mountainous regions

This review synthesizes recent advances in the study of geohazard chains in mountainous terrains, emphasizing both formation mechanisms and approaches to risk assessment. Geohazard chains are defined as cascading processes where an initial event, such as an earthquake or extreme rainfall, triggers a sequence of secondary hazards with strong spatiotemporal linkages. The review begins by clarifying the concept and classification of hazard chains and distinguishing them from multi-hazard scenarios that lack causal continuity. Mechanistic studies have identified controlling factors such as loose material supply, hydrological thresholds, and seismic disturbance. In the field of risk assessment, diverse frameworks—including event trees, Bayesian and complex networks, system dynamics, and machine learning—have been tested, each with strengths and limitations. Current evidence shows that the integrated risk of chains exceeds that of isolated hazards, highlighting the need for dynamic models capable of capturing multi-hazard feedbacks. Future progress will depend on improved mechanistic coupling of rainfall- and earthquake-induced processes, integration of multi-source monitoring data, and collaborative prevention strategies tailored to mountain communities.