Characteristics and causes of the landslide on July 23, 2019 in Shuicheng, Guizhou Province, China
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Siyuan Ma I Chong Xu I Xiwei Xu I Xiangli He I Haitao Qian I Qisong Jiao I Wei Gao I Huaining Yang I Yulong Cui I Pengfei Zhang I Kai Li I Hongrong Mo I Jun Liu I Xiuwei Liu
Characteristics and causes of the landslide on July 23, 2019 in Shuicheng, Guizhou Province, China
Abstract At 8:40 p.m. (Beijing time) on July 23, 2019, a large landslide occurred at Jichang, a village in Shuicheng, Guizhou Province, China, resulting in 42 deaths, 9 missing people, and 21 buildings buried. Field investigation and unmanned aerial vehicle (UAV) photography allow us to characterize this slope failure and analyze its process and causes. Initially, the materials detached from the mountainside and slid over from the slope. Then, the sliding materials partly accumulated in the middle and upper parts of the slope which were blocked by a convex terrain. The rest turned into a high-speed debris flow, divided by the stable block, and descended along two existing gullies at high velocity, and finally decelerating and accumulating. Based on the high-resolution post-sliding DEM data, the original topography of the study area was reconstructed to estimate the volume of the landslide that was about 1,500,000 m3. Based on a first-order evaluation of the landslide kinematics, the whole sliding process of this event lasted about 60 s, the maximum speed was about 25 m/s, and the average speed was 16.6 m/s, indicating a typical high-speed long-runout debris flow. Analysis suggests that continuous heavy rainfall was the dominant factor to trigger this landslide, and the loose weathered regolith and special local topography were the basic intrinsic factors for this event. Keywords Shuicheng landslide . Landslide-debris flow . Rainfall . UAV . Volume analysis Introduction High-speed landslides can be extremely hazardous due to their high mobility, rapidity, and severity (Delaney and Evans 2015; Wang et al. 2017; Zhou et al. 2013), which have been a focused topic over 100 years (Hsu 1975). This type of landslides is characterized by high vertical drop, rapid movement, and large volume (Hungr and Evans 2004; Setiawan et al. 2019; Yin et al. 2016; Zhen et al. 2016). The earliest study on this issue can be traced back to the 1903 great landslide at Frank, Alberta, Canada (McConnell and Brock 1904; Cruden and Krahn 1978). Although many efforts have been made to clarify mechanisms of highspeed landslides, there still exist some debates (Hu et al. 2019; Mitchell et al. 2015). Here, we present an example, which occurred on July 23, 2019 at Jichang, a village in the Shuicheng county, Guizhou Province, China (26°15′27″N, 104°40′24″E) (hereafter called the Shuicheng landslide), resulting in 42 deaths, 9 missing people, and 21 buildings buried. Immediately after the event, we went to the site to conduct a field investigation and UAV photography (DJ Pro4). The data acquired allows us to characterize this slope failure and analyze its process and causes.
Study area Shuicheng County is located in the central Yunnan-Guizhou Plateau, about 258 km east to Guiyang Ci
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