Monitoring, Early Warning and Deformation Characteristics of Yantu'an Landslide in Yan'an

Yantu'an landslide is located in Wayaogou area, Chengguan Town, Ganquan County, Yan'an City, Shaanxi Province. The front edge of the Yantu'an landslide creep deformation was caused by extreme heavy rainfall in July 2013 in Yan'an. The landslide develops several transverse tension cracks in front edge, which shows signs of revival. In order to carry on the disaster reduction and disaster prevention, as well as the analysis of landslide deformation characteristics and deformation mechanics mechanism, a real-time monitoring system of the Yantu'an landslide has been carried out on October 16, 2013. On May 14, 2014, this landslide became more deformed, the timely warning and forecasting have been carried out, and all the threatened personnel has been evacuated safely. On May 15, the front of the landslide slipped to about 200 m³. The people's life has been protected because of the successful early warning and timely evacuation. Deformation process of this landslide has been divided into four stages by monitoring results:initial deformation stage, accelerative deformation stage, unstable deformation stage and decelerating deformation stage. Rainfall is the main inducing factor of this landslide deformation instability. In addition, the excavation and freeze-thaw action of slope foot also have an important influence on landslide deformation and instability.