中国强震发生带地震构造的几点思考  

Some Thoughts on the Seismic Tectonics of Strong Earthquake Occurring Sections in China

作　　者：李玶[1] 黄广思[2] 杨美娥[3] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]中国地震局武汉地震研究所,武汉430000 [3]中国科学院地质研究所,北京100029

出　　处：《高校地质学报》2001年第3期245-256,共12页Geological Journal of China Universities

摘　　要：强震发生带是指全新世 (约 1.2万年 )以来发生过和将来还会发生M≥ 6级地震的地带。中国强震发生带的动力源主要来自印度板块向NNE的顶撞作用 ,而太平洋板块向西俯冲则次之。板块、断块及锒嵌其间的缝合线、深大断裂带 ,组成了窗棂结构 ,受力时“窗棂”(缝合线、深大断裂 )发生错动 ,而“窗”(板块、断块 )的内部则相对稳定。第四纪以来 ,以我国西南鲜水河———小江断裂带为例 ,在Q1、Q2 时期因断裂带作左旋扭动 ,在拉张区形成许多断陷盆地 ;到Q3由于地应力方向改变 ,运动加剧 ,使不同方向断裂互相贯通 ,活动延续至今 ,称之为活动断裂带。强震多发生在活动断裂带的特殊部位 ,震中区地面强烈变形 ,表现为毗邻地段猛烈升降、地堑地垒系和断头河等。由古地震研究得知Q4 以来强震常在原地多次重复 ,且震级相近。由台湾 1999年集集地震和云南195 5年鱼地震的加速度等值线和等烈度线图形对比 ,建筑物破坏程度和昔格达层变形对照 ,得出强震构造变形机理乃系“夹心饼干”似的三层结构所致 ,三层即是断层的二盘和其所夹持的断层破碎带 ,后者是地应力聚集和释放的场所 。The term strong earthquake occuring sections (SEOS) is used to specify those places where strong earthquakes (M≥6) have occurred since Holocene, and will occur repeatedly in the future. The crust of China consists of several plates or blocks. Their boundaries are mostly large fault zones. Quaternary active faults have been forming and developing along the zones under the united effect of India Plate's collision towards NNE and Pacific Plate's subduction towards W. Southwest China is an area where SEOS are concentrated. During Q 1 and Q 2, the Sichuan-Yunnan (Rhombus) Block was pushed to SSE, so that left lateral strike slipping took place in the Xianshuihe Fault Zone and Xiaojiang Fault Zone. Some fault basins were formed in the tensional areas nearby these zones. During Q 3, due to change of tectonic stress direction, Xiaojiang Fault Zone linked with Xianshuihe Fault Zone and formed a huge curve fault zone, where a lot of SEOS are located. Activation of faults in Q 3 has an universal significance. All the faults last to the current time, and the faults are called active faults for this reason, SEOS are located at specific sections of the active faults. Epicenters in SEOS express characteristics in the tectonophysics and geomorphology. Widely developed graben horst system, long range of remaining fault hills, head cut rivers, remarkable differential in relief by accending and descending of the operate fault banks in the area where strong earthquakes occurred, are some obvious samples. In SEOS, strong earthquakes of similar magnitudes repeated in the same places in certain temporal interval. The model of the processes is 'breaking-healing-breaking again-healing again'. According to the similarity of the map patterns of iso value of acceleration of Jiji Earthquake (9.21. 1999, Taiwan, China) and the iso intensity for Yuzha Earthquake (1955, Sichuan, China), evident differences of buildings damage between in fault zones and out of fault zones and deformation of young deposition layers, the d

关 键 词：强震发生带 “窗棂”结构 活动断裂带 台湾集集地震 鱼Zha地震 中国 地震构造 

分 类 号：P315.2[天文地球—地震学]