Assessment of prospective hazards resulting from the 2017 earthquake at the world heritage site Jiuzhaigou Valley,Sichuan, China

摘要

On August 8,2017,a Ms =7.0 magnitude earthquake occurred in the Jiuzhaigou Valley,in Sichuan Province,China (N:33.20°,E:103.82°).Jiuzhaigou Valley is an area recognized and listed as a world heritage site by UNESCO in 1992.Data analysis and field survey were conducted on the landslide,collapse,and debris flow gully,to assess the coseismic geological hazards generated by the earthquake using an unmanned aerial vehicle (UAV),remote-sensing imaging,laser range finders,geological radars,and cameras.The results highlighted the occurrence of 13 landslides,70 collapses,and 25 potential debris flow gullies following the earthquake.The hazards were classified on the basis of their size and the potential property loss attributable to them.Consequently,14 large-scale hazards,30 medium-sized hazards,and 64 small hazards accounting for 13％,28％,and 59％ of the total hazards,respectively,were identified.Based on the variation tendency of the geological hazards that ensued in areas affected by the Kanto earthquake (Japan),Chi-chi earthquake (Taiwan China),and Wenchuan earthquake (Sichuan China),the study predicts that,depending on the rain intensity cycle,the duration of geological hazard activities in the Jiuzhaigou Valley may last over ten years and will gradually decrease for the following five to ten years before returning to pre-earthquake levels.Thus,necessary monitoring and early warning systems must be implemented to ensure the safety of residents,workers and tourists during the construction of engineering projects and reopening of scenic sites to the public.