北祁连-河西走廊地区垂直形变与构造应力场关系的初步研究——三维有限元拟合结果分析  

THE RELATIONSHIP BETWEEN VERTICAL DEFORMATION AND TECTONIC STRESS FIELD IN NORTH QILIAN MOUNTAIN-HEXI CORRIDOR REGION-AN ANALYSIS BASED ON 3-D FINITE ELEMENT METHOD

作　　者：刘峡[1] 黄立人[2] 杨国华[2] 孙东平[2] 张四新[3] 韩月萍[2] 

机构地区：[1]中国科技大学地球与空间科学系,合肥230026 [2]中国地震局第一地形变监测中心,天津300180 [3]中国地震局第二地形变监测中心,西安100054

出　　处：《地震地质》2003年第2期307-316,共10页Seismology and Geology

基　　金：国家重点基础研究发展规划项目 (G19980 4 0 70 3);科技部"九五"项目 (96 9130 10 10 6 )共同资助

摘　　要：根据已知的地震地质资料对北祁连 -河西走廊及相邻区进行了三维有限单元剖分 ,在线弹性条件下 ,拟合了其 2 0a来垂直运动的总体趋势。计算表明 ,北祁连 -河西走廊地区垂直形变的拟合结果 ,与背景应力场的约束形式和变化特征密切相关 ,其中采用构造应力场增强作为加载条件以及稳定地块作为位移约束条件得出的拟合结果与该区域 2 0a来垂直运动的整体分布特点相一致。在此基础上 ,进一步得到其背景应力场增强的量值估算 ,其中SN方向的压力变化为 +0 .11MPa(压为正 ) ,EW方向的压力变化为 +0 .0 4MPa(压为正 ) ,EW方向的压力变化量是SN方向的 3倍左右。此外 ,根据计算得到的 10～ 15km深处剪应力增量Δγxy的分布情况 ,对比中强地震震源分布可以看出 ,剪应力增量与震源在空间分布上有一定的关联性。震源往往分布在剪应力增量变化较剧烈处 。Based on the seismic and geologic information available, North Qilian and Hexi Corridor area is divided into a number of 3 D finite elements. On the assumption of linear elastic model, the general tendency of vertical deformation spanning about 20 years in this area is simulated. The simulated results of this area bear a close relation with boundary condition and variation of background stress field. Among them, the result obtained by taking the increment of tectonic stress field as loading condition and stable block as displacement boundary condition, is in good consistence with the general distribution of vertical deformation in this area in the past 20 years. Based on this acknowledgement, the increment of the background stress field is estimated. The pressure change along N S direction is +0.11MPa, and that along E W direction is +0.04MPa (compressive pressure is positive). The quantity of the pressure change along E W direction is three times of that along N S direction. In addition, by comparing the distribution character of the obtained incremental shear stress (Δ γ xy ) field with that of the foci of mid strong earthquakes, we find that there is a certain relationship between the incremental shear stress and the location of these earthquake foci. The fact that the earthquake focus is usually located in the area of severe variation of shear stress increment proves that the simulated tectonic stress field is reasonable to some extent.

关 键 词：北祁连-河西走廊地区 垂直形变 构造应力场 三维有限单元 剪应力增量 地震地质资料 震源 

分 类 号：P315.727[天文地球—地震学]