摘要
砂土液化是震后灾害的主要形式之一,因此震后进行详细的砂土液化分布规律和发育特征的地表调查,具有重要意义.为了揭示定日地震产生的砂土液化特征,在震后针对定日地区进行了详细的遥感解译、野外调查,获得以下结果:(1)2025年1月7日定日M_(S)6.8级地震中,南部朋曲河谷、中部丁木措湖边、到北部空摸措东南侧均发育有砂土液化.这可能指示了本次地震形成了一个砂土液化层.在本次地震中朋曲河两岸和丁木措东岸砂土液化导致的地面破坏以横向扩展为主;而在朋曲河床、丁木措东岸冲积扇边缘、空摸措东南侧地面破坏以液化沙丘为主.(2)基于野外观察和构造应力场分析,认为本次地震中的砂土液化变形存在一个动态的发育过程.在构造应力和重力作用下,形成南北向张裂缝,由于振动使砂土液化,部分液化体随南北向张裂缝喷出.由于坡度较为平缓,产生了横向扩展.表层块体发生碰撞和挤压,在部分位置由于强烈的挤压碰撞,产生了东西向的张裂缝,液化体随之涌出,发育近东西向线状液化沙丘.
Sand liquefaction is one of the main forms of post-earthquake disasters,so it is of great significance to conduct a detailed surface survey of the distribution patterns and development characteristics of sand liquefaction after an earthquake.To reveal the characteristics of sand liquefaction caused by the Dingri earthquake,detailed remote sensing interpretation and field investigation were carried out in the Dingri area after the earthquake,and the following results were obtained:(1)During the M_(S)6.8 Dingri earthquake on January 7,2025,sand liquefaction was observed in the southern Pengqu Valley,along the shores of Dingmu Co in the central area,and on the southeast side of Kongmucuo in the northern region,which suggests the formation of a widely distributed liquefied sand layer in the strata during this earthquake.In this event,ground failures caused by sand liquefaction along both banks of the Pengqu River and on the east shore of Dingmu Co were mainly characterized by lateral spreading.In contrast,ground failures in the riverbed of Pengqu,the edge of the alluvial fan on the east shore of Dingmu Co,and the southeast side of Kongmucuo were dominated by liquefaction-induced sand dunes.(2)Field observations and analysis of the tectonic stress field suggest that the sand liquefaction deformation in this earthquake underwent a dynamic developmental process.Under the influence of tectonic stress and gravity,north-south oriented tensional fractures formed.The sand liquefied due to the librations,and some liquefied material was ejected along these north-south fractures,resulting in lateral spreading due to the gentle slope.Blocks on the surface collided and compressed with each other.In some locations,intense compression and collision led to the formation of east-west oriented tensional fractures,through which liquefied material surged out,forming nearly east-west oriented linear liquefaction sand dunes.
作者
李智超
吴中海
韩帅
高扬
黄婷
凡福新
田婷婷
陆诗铭
Li Zhichao;Wu Zhonghai;Han Shuai;Gao Yang;Huang Ting;Fan Fuxin;T ian Tingting;Lu Shiming(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;School of Earth Sciences and Space,Peking University,Beijing 100871,China;Minnan Normal University,Zhangzhou 363000,China;School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,China)
出处
《地球科学》
北大核心
2025年第5期1830-1841,共12页
Earth Science
基金
国家自然科学基金项目(Nos.42472287,42402229,42202259).
