Development characteristics and formation mechanism of Deqin Riyinka landslide in Yunnan

The Deqin area of Yunnan is located in the vertical valley of the Hengduan Mountain along the southern extension of the Tibetan Plateau.Most villages and towns are more than 3000 meters above the sea level.The geological structure there is complex, rock masses are broken, and landslides, collapses, debris flows and other geological disasters are frequent and prone to occur.Deqin is hence a typical high-altitude poverty area in the three districts and three prefectures.In accordance with the requirements of strengthening geological disaster investigation and monitoring and early warning in the Ministry of Natural Resources 2020 Plan for Poverty Alleviation Work and through the investigation and monitoring of geological disasters in this area, the distribution characteristics and mechanism of and disasters of geological disasters in high-altitude poor mountainous areas were identified.With Riyinka landslide as an example, the authors adopted "air-space-ground" integrated technology in combination with the engineering geological conditions of the landslide study area, investigated and analyzed the potential instability mechanism and landslide movement characteristics of the landslide, and focused on the investigation, evaluation and monitoring of geological disasters.Early warning, emergency prevention and other systems were carried out, and several understandings were obtained as follows:①Landslide instability is closely related to human engineering activities such as surface precipitation, ice and snow melting, freezing and thawing cycles, and cutting slopes and building houses; ②According to landslide deformation characteristics, the authors generalized the disaster-pregnancy and instability procese, i.e., local sliding stage at the leading edge → creeping-cracking stage → overall sliding stage → scraping and covering stage.③Based on the analysis of the development characteristics of landslide disasters in the Lancang River Basin, the authors made a disaster model of such landslides, and put forward the prevention and control measures and suggestions for tackling geological disasters in high-altitude poverty areas in the three districts and three prefectures.Scientific disaster prevention and mitigation provide technical support and scientific basis and can effectively protect the lives and property of the poor.