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Researcher Xu Chong participated in investigation of the Jinshajiang Baige landslide

2019/8/21 11:01:15

On October 10, 2018, a large ancient landslide accumulation body near Baige township on the upper reaches of the Jinsha River at the border between Sichuan and Tibet became partially unstable, forming a large landslide (Figures 1 and 2) and blocking the Jinsha River. The landslide dam burst on October 13, the water level of the barrier lake continued to drop, and the hidden danger of a dam break was removed. However, on November 3, the back edge of the landslide slipped again and the new landslide blocked the drainage channel of the dam, again completely blocking the Jinsha River. Subsequently, the barrier lake was removed by manual digging of a drainage channel. From December 5 to 7, 2018, Researcher Xu Chong of our institute assisted researchers from the Institute of Crustal Dynamics in the investigation of the Jinshajiang Baige landslide. They analyzed the formation of the Baige landslide and made a preliminary judgment on its future evolution by a combination of comparison of multiple time-series optical satellite images, identification of ultra-high resolution UAV aerial photographs, continuous monitoring by ground-based radar, and other technical means. The results show that the Baige landslide is a large accumulation–bedrock mixed landslide, and occurred on the site of a large ancient landslide accumulation. The ancient slope did not move at a distance, therefore, the original structure and sequence of bedrock were well preserved. The Baige landslide was caused by a sudden instability of the left half of the ancient landslide after it experienced long-term creep (horizontal sliding displacement of at least 50 meters within 8 years) under its own gravity and reached its stability limit. The landslide was not directly affected by earthquake or rainfall. The distribution of cracks on the back edge and both sides of the landslide and continuous monitoring data from ground-based radar indicate that large-scale sliding similar to that on October 10 and November 3 is less likely to occur in the near future. Because of the large number of cracks in the back edge and the slope body on both sides, local instability is very likely to occur under rainfall conditions. Therefore, it is suggested that long-term monitoring of deformation in this landslide area by combining space-borne optical and radar images should be conducted. It is further suggested that monitoring by unmanned aerial vehicles or ground-based radar should be carried out with immediate effect during the rainy season or if further deformation is found.

Figure 1 Photograph of the Jinshajiang Baige landslide area

Figure 2 3D image of the Baige landslide