地震三角形分类图解法与华北地区地震成因分析  

The method of triangle seismic classify and analysis on the seismic cause in the northern China

作　　者：马文涛[1] 徐锡伟[1] 徐平[2] 于贵华[1] 

机构地区：[1]中国地震局地质研究所,北京100029 [2]北京市地震局,北京100080

出　　处：《地球物理学进展》2004年第2期379-385,共7页Progress in Geophysics

基　　金：北京市"十五"重点攻关项目(H030630090190)资助;中国地震局地质研究所论箸2004B0027.

摘　　要：　选取华北地区的近期震源机制参数资料,改进地震分类的三角形图解法,提出了地震的二级分类法和依据,详细划分了带正断裂型、逆断裂型、走滑型分量的混合型二级类型等多种断层机制,并讨论了华北地区地震成因.结果表明:一级地震类型以走滑机制为主,其次为正、逆断层机制和过渡型,而二级地震类型多为带其它分量的混合型机制、正、逆断层机制和过渡型,走滑型机制的地震数量不到一半.说明华北地区现今地壳脆性变形虽然以走滑机制为主,但是大多数地震属带其它分量.在NEE-SWW向的水平主压应力作用下,形成了NWW向的张家口-蓬莱地震密集带和与此相共扼的一系列NE向或NEE向具有强震机制的构造,以走滑动机制或带其它分量的走滑动机制为主,并在一系列的第三纪、第四纪断陷盆地边缘或平原中发生带有走滑分量的正断裂或带正断层分量的走滑型机制的地震,表明断裂上盘在侧向运动的同时,也存在着一定量的向下运动,继续进行着盆地、平原的"生长";而在太行山及晋北山区,也同样存在着慢速隆起.这是现代华北地区山区、盆地差异运动的一种形式,反映出华北地区地壳变形是在复杂力学环境背景下发生的和具有复杂的发生、发展和变化过程.The new triangle diagram method is modified by proposing quantified a second\|order for classification of focus mechanism in order to more properly describe faults behaviour which is more comely featured by oblique slip in dependence of relative proportion of vertical part of main stress axis. There are pure strike\|slip, pure reverse, pure normal, strike\|slip, reverse, normal, strike\|slip with reverse, strike\|slip with normal, reverse with strike\|slip, normal with strike\|slip, reverse with steep or gentle slope, normal with steep or gentle slope in the classification of focus mechanism. The regional tectonic analysis in northern China have been discussed. The type of first order of seismic mechanisms is mainly strike\|slip, secondly reverse and normal. The second order type is mainly oblique slip and the number of strike\|slip earthquakes is less than a half. The modern crustal deformation is dominated by horizontal displacement, which give birth to the NWW\|trending Zhangjiakou\|Penglai seismic belt and a series of NE/NNE\|trending structures that conjugate with the former and bear strong seismic mechanisms in North China. The seismic mechanisms are mainly strike\|slip type or accompanied by normal or reverse proportion. Earthquakes along the basins' boundaries or in the inner of the Plain are normal type with strike\|slip proportion or strike\|slip type with normal proportion, which imply the hangingwalls of faults subside while they move horizontally. In Taihangshan and north Shanxi, earthquakes are the types of strike\|slip, strike\|slip with reverse proportion or reverse\|slip with strike proportion, resulting in slow upheaving. In this way, the discrepancy between mountains and basins occurs, reflecting complex dynamic background for crustal deformation and complicated progress of occurring, developing and changing.

关 键 词：地震分类 三角形图解法 震源机制解 发震成因 华北地区 

分 类 号：P315[天文地球—地震学]