Field survey of a catastrophic high-speed long-runout landslide in Jichang Town, Shuicheng County, Guizhou, China, on Ju
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Weihua Zhao I Rui Wang I Xiuwei Liu I Nengpan Ju I Mingli Xie
Field survey of a catastrophic high-speed long-runout landslide in Jichang Town, Shuicheng County, Guizhou, China, on July 23, 2019
Abstract On July 23, 2019, a large catastrophic landslide was triggered by heavy rainfall at Jichang Town, Shuicheng County, Guizhou, China. This high-speed landslide was characterized by a short slip time, long slide distance, and great destructiveness. In less than 2 min, about 2 million m3 of cataclastic basalt soil failed with a runout of about 1.25 km over a total vertical distance of about 465 m. The landslide destroyed 21 houses and caused 42 fatalities with 9 people missing. To understand the possible mechanisms for the high-speed and long-runout behavior of the landslide, a detailed field survey was conducted. A preliminary analysis was performed on the movement characteristics and formation mechanism of the landslide based on combining data from multitemporal optical satellite remote sensing images, aerial photography from an unmanned aerial vehicle, and InSAR. The historical remote sensing images, InSAR results, and geological monitoring data indicated no obvious deformation signs before the landslide, which implies that it occurred suddenly. The landslide was probably primarily induced by heavy rainfall, while the direct impact of road excavation was small. The terrain controls motion characteristics of the landslide and air blast effect is still visible at the leading edge of the landslide. The results of this study may provide basic data for further research on the mechanisms for landslide initiation and movement. Keywords Jichang landslide in Shuicheng County . High speed . Long runout . InSAS analysis of historical deformation . Field investigation after landslide Introduction Long-runout landslides are a common geological feature in various environments. They are defined by traveling further than expected from simple frictional models (Legros 2002). This high mobility makes them very hazardous (Crosta et al. 2003; Huang 2009; Xu et al. 2010; Yin et al. 2011; Xu et al. 2012; Yin and Xing 2012; Watkins et al. 2015). In the last decade, the Chinese government has made many efforts to prevent or mitigate such landslides by establishing geohazard early-warning systems with weather forecasting and educating residents in mountainous areas (Yin et al. 2010). These efforts have effectively improved the early identification of some landslides and facilitated timely evacuation. Nevertheless, the loss of lives and properties from long-runout landslides has continued to increase in China with disasters such as the Zhenxiong landslide (Yin et al. 2016) and Maoxian landslide (Xu et al. 2017; Zeng et al. 2018); this is mainly due to urban development, land-use change, and political issues as well as climate change. On the night of July 23, 2019, a large, high-speed, long-runout landslide suddenly struck Pingdi Village, Jichang Town, Shuicheng County, Guizhou Province (26° 15′ 35″ N, 104° 40′ 13″ E). As shown
in Fig. 1, th
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