华北渤海湾盆地区大震发震构造的基本特征  

FEATURES OF SEISMOGENIC STRUCTURES OF GREAT EARTHQUAKES IN THE BOHAI BAY BASIN AREA,NORTH CHINA

作　　者：徐杰[1] 周本刚[1] 计凤桔[1] 高战武 陈国光[1] 孙建宝[1] 

机构地区：[1]中国地震局地质研究所,活动构造与火山重点实验室,北京100029 [2]中国地震灾害防御中心,北京100029

出　　处：《地震地质》2012年第4期618-636,共19页Seismology and Geology

基　　金：大型先进压水堆核电站国家科技重大专项"CAP1400安全审评技术及独立验证试验"(2011ZX0600201015)项目资助

摘　　要：发震构造是地震地质研究的核心内容。渤海湾盆地是华北地震活动强烈的地区,记载有7级以上大震6次。1966年邢台7.2级地震后,许多研究者认为该区大震的发震构造是新生代发育的正断裂及其控制的断陷盆地,但1986年有人提出断陷盆地之下的高角度深断裂是发震构造的新看法。根据多年来盆地构造和地震构造研究的大量成果,通过对渤海湾盆地古近纪断陷与中新世中期(12～10MaBP)以来新构造发育2个阶段的构造几何学特征和构造属性,以及其动力条件的对比分析,並结合大震区构造的剖析,较系统地阐述发震构造。其中最根本的是,渤海湾盆地不同构造阶段具有不同的动力条件,形成不同体制的构造系统。断陷阶段盆地区受NW-SE向拉张作用,在地壳上部形成由大量缓倾正断裂及其控制的断陷盆地组成的伸展构造系统;新构造阶段在NEE至近EW向水平挤压作用下,正在发育1套由NE向右旋平移和NW向左旋平移的断裂组成的地壳共轭剪切破裂系统。前者是作为先存构造而存在的,后者对于前者既有叠加、改造,也有不受其控制,具有继承和新生的二重性,是控制地震孕育和发生的主要地质构造。Seismogenic structure is the core of seismo-geology. The Bohai Bay Basin area in North China is highly active in terms of seismicity,where six earthquakes of M/〉 7.0 have occurred. After the 1966 MT. 2 Xingtai event,some researchers suggested that the seismogenic structure of this earthquake was associated with the Cenozoic normal faults and the fault-depression basins the faults controls. In 1986,however,some authors proposed that this quake should be attributed to a high-angle fault be- neath the basin. The purpose of this paper is to give a systematic elucidation on seismogenetic structures in the Bohai Bay Basin area,North China,which are built on the geological studies in combination with ex- ploration to deep structures in the seismic areas. The paper analyzes and compares the geometric fea- tures and structural attributes as well as their dynamic conditions of the Bohai Bay Basin in two evolu- tion stages,i, e. the Eogene when the fault-depression formed and mid Miocene（ 12 ~ 10Ma）when the neotectonics developed. It emphasizes the distinct dynamic conditions in these two stages that formed different structural systems. In the stage of fault-depression,this area was subject to extension in NW -SE direction,which produced many gentle normal faults in the shallow subsurface that characterized the fault-bounded depression basins. While in the neotectonic stage,a set of conjugate fault system consisting of NE-trending right-lateral slip-strike faults and NW-directed left-lateral strike-slip faults were generated by the NEE to approximately EW-orientated horizontal compressional stresses. The structure of the first stage was pre-existing, while that of the second stage has both inheritance and va- riance to the first stage,i, e. superposition and reform,which accounts for the gestation and occurrence of the present-day major earthquakes in this area.

关 键 词：伸展构造 新生断裂带 大震发震构造 华北 渤海湾盆地 

分 类 号：P315.2[天文地球—地震学]