A catastrophic landslide triggered debris flow in China's Yigong: factors, dynamic processes, and tendency.

A disaster of a catastrophic landslide triggered a debris flow with a scale of 0.3 billion m3 that occurred in the Zhamunong gully of Yigong on April 9th, 2000. It is of great scientific and engineering significance to study the main controlling factors and dynamic processes of this disaster, and the future development trend of similar hazards. Firstly, the precipitation, earthquake and temperature data before the event and seismic wave data after the event were collect. Secondly, a multi-dimensional approach on the data for finding the factors, dynamic processes and tendency of a catastrophic landslide triggered a debris flow in Zhamunong gully was applied, including the standard precipitation index and effective peak acceleration calculation methods, fast Fourier transform, landslide stability, MacCormack- TVD finite difference method and FLAC numerical simulation method. The results are shown as follows. (1) The main controlling factors of this disaster were the long-term freeze-thaw cycle, dry-wet cycle, and a middle magnitude earthquake. (2) Based on the ground vibration spectrum of 2000 disaster recorded by the Linzhi seismic station, the dynamic processes are the joint and crack development process, the crack fracture and sliding process, the landslide translating into the debris flow, the movement and deposition of the debris flow. (3) The density and the average velocity are 2.0 t·m-3 and 30.12 m·s-1, respectively, and the discharge is shown with the process of first increases and then decreases. (4) Similar catastrophic landslide triggered debris flow would happen in Zhamunong gully in the future. The research results are useful in establishing a foundation for further study on the dynamic mechanism and reduction countermeasures of a catastrophic landslide triggered by debris flow. [ABSTRACT FROM AUTHOR]