摘要
破坏性地震等自然灾害不仅会引起区域生态环境恶化,导致水土流失和地方贫困化,更为直接的影响就是人民生命财产的损失及对民居等地面建筑的破坏和地表变形.通过野外现场地面调查综合分析了2025年1月7日藏南定日6.8级地震形成的地表变形特征,地面沉降及造成的建筑物倒塌破坏情况.沿丁木错断裂从北海拔5500多米垂向位移>185 cm向南至丁木错东海拔4200多米垂向位移<120 cm,整体由北向南的垂向位移强度有所减小;北段断层陡坎倾向西,丁木错断裂上盘整体下降,局部地段呈台阶式依次下降,导致冰蚀U型谷中冰水沉积物及坡脚冲洪积物出现最高可达3 m的陡坎;干枯的牛粪、冻土鼓包及巨大的冰漂砾被左行错断,显示此次地震还有较明显的走滑特征.丁木错东更新世洪冲积物中出现南北延伸较长且东西宽度达50 m的地表变形,以中部塌陷呈地堑式张性破裂为主,张性破裂出现的陡坎高度一般不超过120 cm,在张性破裂的前缘端即靠近丁木错局部地段还发育高约50 cm的挤压隆起和地震鼓包.位于地表地裂缝中心地带的吉翁村和古荣村等村庄是本次地震受灾最为严重的村区.结合区域地质背景分析表明,定日地震是伸展构造控制的浅源破坏性地震,新生代地幔热物质的底辟上涌,活化了以南北向丁木错平移正断层及近东西向藏南拆离系为代表的伸展构造,从而在这些伸展构造交汇部位释放能量引起地震.
Destructive earthquakes and other natural disasters not only cause deterioration of the regional ecological environment,but also lead to soil erosion and local poverty,but also have a more direct impact on the loss of people′s lives and property,as well as the destruction and deformation of ground buildings such as residential buildings.The Surface deformation characteristics,ground subsidence,and building collapse caused by the Ms 6.8 earthquake occurred in Dingri County,southern Surface Deformation Characteristics and Seismo-Tectonics of the 2025 Dingri Ms6.8 Earthquake in Southern Xizang on January 7,2025 were comprehensively analyzed through field investigations.The vertical displacement intensity along the Dingmu Co fault decreases from vertical displacement of over 185 cm at an altitude of over 5500 meters in the north to vertical displacement of less than 120 cm at an altitude of over 4200 meters in the east of Dingmu Co;The northern section has a westward drop,which is due to the overall descent of the upper plate of the Dingmu Co fault,with some sections descending in a stepped manner,resulting in steep slopes of up to 3 meters for ice water sediments and slope foot alluvial deposits in the ice eroded U-shaped valley;Occasionally,dry cow manure,Permafrost bulge,and huge ice debris being left displaced,indicating that this earthquake also had obvious strike slip characteristics.A Surface deformation with a north-south extension and an east-west width of up to 50 meters appeared in the alluvial deposits of the eastern Pleistocene in Dingmu Co,characterized by a central collapse and overall westward subsidence.The steep slope of the tensile rupture generally does not exceed 120 cm,and up to 50 cm squeezing uplift and seismic bulges are also developed at the leading edge of the tensile rupture,near the local section of Dingmu Co.The villages of Jiweng and Gurong,located in the center of the surface fissure,were the most severely affected by the Dingri earthquake.Except for a few cement and brick houses,most of the houses collapsed,making them the most severely affected villages in this earthquake.Based on the analysis of regional geological background,the Dingri earthquake is a shallow source destructive earthquake controlled by extensional structures.The upwelling of mantle thermal material in the Cenozoic era activated extensional structures represented by the north-south Dingmu Co strike-slip normal fault and the nearly east-west Tibetan southern detachment system,releasing energy at the intersection of these extensional structures and causing earthquakes.
作者
刘德民
张妍
汪海明
姜淮
赵悦
王墩
杨巍然
Liu Demin;Zhang Yan;Wang Haiming;Jiang Huai;Zhao Yue;Wang Dun;Yang Weiran(School of Earth Sciences,China University of Geosciences,Wuhan 430074,China;School of Future Technology,China University of Geosciences,Wuhan 430074,China)
出处
《地球科学》
北大核心
2025年第8期3270-3283,共14页
Earth Science
基金
深地国家科技重大专项(No.2024ZD1000205-03-04)
基于动力学模型的中长期地震数值预测关键技术研究(No.20230110115)。
关键词
藏南
定日地震
地表变形
成因机制
伸展构造
天然地震
South Surface Deformation Characteristics and Seismo-Tectonics of the 2025 Dingri Ms6.8 Earthquake in Southern Xizang
Dingri earthquake
surface deformation
genetic mechanism
extensional structure
earthquake
