Investigation and dynamic analysis of a catastrophic rock avalanche on September 23, 1991, Zhaotong, China
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At 6:10 p.m. on September 23, 1991, a catastrophic rock avalanche occurred in Zhaotong, Yunnan, southwestern China. Over 216 people were killed when the Touzhai village was overwhelmed directly in the path of the landslide. The landslide involved the failure of about 12 Mm3 of jointed basaltic rock mass from the source area. The displaced materials ran out a horizontal distance of 3650 m over a vertical distance of 960 m, equivalent to a Fahrböschung of 14.7°, and covered an area of 1.38 km2. To provide information for hazard zonation of similar type of potential landslides in the same area, we used a dynamic model (DAN-W) with three alternative rheological models to simulate the runout behaviour of the displaced landslide materials and found that a combination of the frictional model and Voellmy model could provide the best performance in simulating this landslide. The simulated results indicated that the duration of the movement is estimated at about 175 s for a mean velocity 21 m/s.
KeywordsRock avalanche Long runout Dynamic analysis DAN-W model
This study was supported by the National Natural Science Foundation of China (No. 41272382 and 41372332) and National Science Fund for Distinguished Young Scholars (No. 41225011). We are grateful to Prof. O. Hungr for supplying a copy of the DAN-W software.
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