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

Jun Li,Ningsheng Chen,Mei Liu,Weiyu Wang,Yuandi Zhao

doi:10.15446/esrj.v24n1.78094

Abstract

A Catastrophic Landslide Triggered Debris Flow (CLDF) hazard with a scale of 0.3 billion m3 occurred in the Zhamunong gully on April 9th, 2000. It is of great scientific and engineering significance to study the main controlling factors and dynamic processes of this CLDF, and the future development trend of similar hazards. First, we collect the data of the prehazard precipitation, temperature and earthquake, as well as the seismic waves generated by the disaster. Second, we use multiple methods on the data, including the EPA and SPI computing methods, Fast Fourier transform (FFT), the engineering geological survey, the calculation method of landslide stability, the FLAC numerical simulation method and rock mechanics experiment, etc. Third, the processed data is analyzed, and the results are shown as follows: (1) The motivating factors of the 2000 CLDF were a long-term freeze-thaw cycle, a dry-wet cycle and an earthquake. It is reasonable that the Ms 4.8 earthquake was a direct inducing factor before the occurrence of the 2000 CLDF. (2) Based on the ground vibration spectrum recorded by the Linzhi seismic station, the dynamic processes of the 2000 LTDF have four processes, which are the joint and crack development process in the landslide, the crack fracture and sliding process, the landslide translating into the debris flow and the movement and deposition of the debris flow. (3) The density of the 2000 CLDF is 2.0 t·m-3, the average velocity of the 2000 CLDF is 30.12 m·s-1, and the discharge process of the 2000 CLDF first increases and then decreases. (4) Based on the adequately internal and external geological conditions, a CLDF of the Zhamunong gully may occur in the future. The research results are useful in establishing a foundation for further study on the dynamic mechanism of CLDFs and hazard reduction countermeasures.

Highlights

A Catastrophic Landslide Triggered Debris Flow (CLDF) refers to a chain of landslides with a volume of more than 1×107 m3 transforming to a high-speed and long distant debris flow after detaching from the parent rock due to the landslide’s enormous potential energy (Huang and Fan, 2013, Chen et al, 2018, Samodra et al, 2018)
(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
At 20:00:11.95 on April 9th, 2000 (Local time), a catastrophic landslide triggered debris flow that occurred in the Zhamunong gully in Yigong (Wang and Lu, 2002, Shang et al, 2003, Evans and Delaney, 2011)

Summary

Introduction

A Catastrophic Landslide Triggered Debris Flow (CLDF) refers to a chain of landslides with a volume of more than 1×107 m3 transforming to a high-speed and long distant debris flow after detaching from the parent rock due to the landslide’s enormous potential energy (Huang and Fan, 2013, Chen et al, 2018, Samodra et al, 2018). At 20:00:11.95 on April 9th, 2000 (Local time), a catastrophic landslide triggered debris flow that occurred in the Zhamunong gully in Yigong (Wang and Lu, 2002, Shang et al, 2003, Evans and Delaney, 2011). The subsequent barrier dam outbreak on June 10th fast formed a flash flood, which resulted in heavy casualties and economic losses (Kang et al, 2017, Wang and Li, 2017, Liu and He, 2018). The G318 national highway was broken off for 76 days, which resulted in two people causalities and a loss of 280 million Yuan (Liu, 2000, Lu, 2002, XuQiang et al, 2012, Schmidt et al, 2015). The flash flood killed 94 people, 2.5 million people were homeless in Ramaphotra, northern India, and traffic broke off in 7 central Indian states (Tewari, 2004, Wang et al, 2016)

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Conclusion