Insights into a Large-Prone Area in the Eastern Margin of the Tibetan Plateau, China—A Case Study Along the Danba Reach of the Dadu River

Landslides, especially large landslides, have been recognized as important contributors to regional geomorphological evolution. There is a large landslide group that includes 32 large landslides in the Danba reach of the Dadu River. These landslides have blocked the Dajinchuan River and Xiaojin River several times in history. And the residue deposit of the large landslides with high activity threatens the life and property of people. To reveal the typical characteristics and mechanism of such landslides, several methods are adopted: remote sensing interpretation; detailed field investigation, and drilling hole of the power station construe. The results show that the large landslides located on the west of the Jintang arcuate tectonic belt which controlled by the NW faults. The distribution of the large landslides includes the Ganhaizi-Suopo reach of the mainstream of the Dadu River, the Waba-Banglang reach of the Geshenzha River, the Aniangzhai-Eman reach of the Xiaojin River, and Erkazi-Gezong reach of the Donggu River and the linear density of the large landslides along the river arrives at approximately 0.56/km, 0.57/km, 0.44/km, and 0.24/km, respectively. The type of large landslides can be divided into 2 types: rock landslides and soil landslides. And the formation mechanism of the large landslides in the Danba reach is divided into 3 types: sliding and fracturing, bending and fracturing, and creepsliding and fracturing. In addition, most large landslides with high–speed characteristics blocked the river to infer that most landslides which were induced by earthquakes event.