Formation mechanism and hazard causes of the Yangya landslide in Yan’an City, Shaanxi

Unreasonable engineering activity is one of the main factors inducing geohazards such as landslides and rockfalls in the loess plateau of northern Shaanxi. The Yangya landslide in Yan’an City is a typical multi-stage, human-induced landslide. According to the failure model and forming factor of the Yangya landslide, it can be concluded that the Yangya landslide occurred through a process of extensional rupture-compressional slip deformation, i.e. a process of development and failure of dragging before pushing. The controlling factors of landslide formation are multiple intense disturbance and existence of the previous slide surface, and the triggering factors include unreasonable excavation, cutting and loading by mankind. Based on the analysis of the disaster causes, the authors think that improper selection of the site, poor consciousness of hazard prevention and incorrect control measures are the main causes of the disaster.