从GPS观测看华北地区的形变场演化

利用1992、1995、1996、2001年的GPS观测资料研究了华北地区形变场的动态演化。华北地区的形变场服从中国大陆板块的整体应力应变场,但也有动态起伏。从主应变场看,1992~1995年,整个华北地区主应变场的方向比较一致,即主压应变方向为NEE-SWW,主张应变方向为NNW-SSE,应变量东部大于西部;但1995~1996年则相反,西部应变量大于东部,而且应变场方向也发生了明显的偏转,西部主压应变方向为NNE-SSW,而东南部地区为NEE-SWW;到1996~2001年西部地区主压应变又恢复到NEE向,整个华北地区应变量也趋于平衡。比较GPS观测与震源机制解给出的华北地区的应力应变场可以看出,其主应力方向基本一致。

STUDY ON EVOLUTION OF DEFORMATION FIELD IN NORTH CHINA AREA WITH GPS DATA

The evolution of crustal deformation field is studied with the GPS data observed in 1992, 1995, 1996 and 2001. The results show that the deformation field in North China is consistent with the stress and strain field in the whole China continent, but changes dynamically. In the period of 1992-1995, the direction of main strain field:NEE-SWW for main compress strain and NNW-SSE for main tensional strain, was uniform in the whole North China, and the strain value in eastern part was larger than that in western part; but reversed in the period of 1995-1996, the strain value in western part was larger than that in eastern part, and there was some rotation in direction:NNE-SSW for main compress strain in west part and NEE-SWW in southeast part; in the period of 1996-2001 the direction in the west part was recovered and the strain values in the whole North China area trended to balance. The stress and strain field given by GPS observation and focal mechanism solution are compared with each other, and the results show that their main principal stress directions are basically consistent.