华北地区近期地壳水平运动与应力应变场特征

利用华北GPS监测网 1 992年、1 995年、1 996年的观测资料 ,应用最小二乘配置给出了华北地区相对水平位移场、应变场的分布图像 .经初步研究表明 :华北地区 1 992-1 995年间的水平位移和应变场表现为整体性不均匀的压性运动 ,1 995- 1 996年测区东部仍以水平压性运动为主 ,但测区西部则主要表现为张性运动 .水平运动 （方向、大小 ）发生显著变化和应变高值区的地带主要位于块体边界带和主要断裂带附近 .燕山断块南边界的北东向断裂存在着较显著的左旋运动 .区内最大剪应变、面膨胀的高值区在天津、北京、唐山一带 .结合非连续变形数值分析方法 （DDA）初步分析认为 ,1 992- 1 995年GPS观测结果显示的华北地区存在东、西部构造应力作用的明显差别 ,华北东部以东西向压应力作用为主 ,而西部的南北向构造应力作用又明显大于东部 .

CHARACTERISTICS OF RECENT HORIZONTAL MOVEMENT AND STRAIN-STRESS FIELD IN THE CRUST OF NORTH CHINA

The data from North China GPS monitoring network in 1992, 1995 and 1996 are used to obtain the distribution patterns of relative horizontal displacement field and strain field in North China area with the aid of least square collocation. Preliminary results show that during 1992-1995 the horizontal displacement and strain fields in North China exhibited an inhomogeneous compressive movement as a whole, during 1995-1996, the east of monitoring area still took horizontal compressive movement as major, but the west of monitoring area mainly appeared tensional movement. The regions where direction and amplitude of horizontal movement remarkably changes and strain is high are mainly located at block boundary belts and nearby main fracture belts. The north east fracture which is the south boundary of Yanshan fault block shows relative notable sinistral movement. Moreover, high value region of maximum shear strain and superficial expansion in this area is in Tianjing, Beijing, Tangshan area. Combining with DDA method, preliminary analysis shows that there exists obvious difference of tectonic stress in the east and the west of North China demonstrated by GPS observation of 1992-1995, the east of North China mainly appears east west direction compressive stress, but the south north direction teutonic stress in the west of North China is obviously larger than that of the east.