Characteristics and runout behaviour of the disastrous 28 August 2017 rock avalanche in Nayong, Guizhou, China

On 28th August 2017, a disastrous rock avalanche occurred in Nayong, Guizhou, China. This catastrophic event killed 35 people and destroyed 23 houses. In this study, the failure process of the avalanche was analyzed using UAV video footage and seismic signal recordings obtained for the pre- and post-failure stages of the landslide. To better understand the possible mechanism of the avalanche and its dynamic characteristics, a numerical simulation was conducted using a dynamic model (DAN3D) to simulate the runout behaviour of the displaced materials. Simulated results indicate that the failure process of the Nayong rock avalanche lasted approximately 30 s; the duration of the failure process is close to that from the UAV video footage and seismic signal recordings (35 s). The duration of movement during the landslide process is estimated to be approximately 90 s with a maximum velocity of 40 m/s. The combined frictional-Voellmy model delivered the most accurate results when simulating this event. The selected models and parameters are expected to aid in clarifying the propagation processes of similar rock avalanches and thus improve the accuracy of hazard prediction in mountainous karst areas.