2015年7月3日新疆皮山MS6.5地震烈度与地震地质灾害特点

摘要

2015年7月3日新疆和田地区皮山县发生的MS6.5地震极震区烈度达到Ⅷ度,砂土液化、地裂缝和崩塌等地质灾害发育。极震区内砂土液化发生范围广泛,地表发生喷砂冒水和边坡的侧向移动,对道路、水利等设施造成了严重的破坏；地裂缝断错多处路面,宽度最大达30 cm,裂缝多呈 NWW走向；崩塌主要发生在高阶地边坡地带,人烟稀少,未造成人员、财产损失。本次地震地质灾害是新疆近十年来MS 6以上较为严重的一次。%Based on field surveys,investigations,and seismo-geological hazards in relation to the Pishan,Xinjiang (MS6.5)earthquake that occurred on July 3,2015,this paper summarizes the associated distribution and develop-ment characteristics of sandy soil liquefaction,ground fissures,collapse,and ground deformation.The seismic intensi-ty of the earthquake is described simply as follows.The earthquake occurred in Pishan county,Hetian City,Xinjiang, and the area of intensity of Ⅵ degrees ranged for 14 580 km2 ,from the west of the city to Kashi City in Yecheng County and to Moyu County,Hetian in the east.The meizoseismal area (Ⅷ degree)was 1 110 km2 ,the length of the major semi-axis was 45 km,and the length of the semi-minor axis was 32 km in the Ⅶ degree area.Seismo-geological hazards relating to this earthquake are mainly distributed in the meizoseismal area,where sandy soil liquefaction is particularly serious,and mainly occurred in Guma and Pixina Towns,Pishan county.The sand blasting nozzle was lin-early distributed throughout a field of low-lying water,causing collapse of the loess side slope in the north of Yapu spring.Pishan county is located in the west of the Kunlun mountains and on the edge of the Tarim basin.The soil in this area is mainly composed of silt and fine sand,gradation is poor and groundwater shallow,thus sand soil liquefac-tion is very serious.Ground fissures and cracks occurring during the earthquake caused slight dislocation,and many can be seen in the meizoseismal area of Pixina town (ground fissures measuring 20 m long and 30 cm wide).Root systems show horizontal right lateral slip in these ground fissures,and the stagger distance is 2 to 7 cm.The road in Pixina Town was crushed and broken,which showed that the earthquake did not cause a rupture zone on the surface, but that compression deformation occurred,which is a type of co-seismic deformation.Although the magnitude of the Pishan earthquake was not large,it resulted in considerable seismo-geologic hazards,particularly sand soil liquefac-tion and ground fissures over a large area.