华北地区地壳水平运动演化特征研究

将华北地区划分为阴山-燕山、鄂尔多斯、山西、太行、冀鲁、胶辽6个块体，应用1995、1996、2001年GPS观测资料研究了这些块体的水平运动演化特征。结果显示出华北地区各块体的相对运动既有继承性也有差异性。华北各块体的总体水平运动趋势是向东漂移，但是个别块体，如鄂尔多斯块体，在1995～1996年期间出现了相对的西向运动。1995～1996年期间华北各块体的运动速率比1996～2001年期间的运动速率要大，特别是阴山-燕山块体。1995～1996年期间鄂尔多斯块体和相邻的山西块体表现为张性分离，阴山-燕山块体之间表现为左旋走滑，这一现象可能与1996～1999年期间发生在华北西北部的3个地震的孕震过程有关。进一步分析表明，加密的连续GPS观测可用于地震预报。

STUDY ON EVOLUTION OF CRUSTAL HORIZONTAL MOTION IN NORTH CHINA AREA

North China area is divided into 6 blocks:Yinshan Yanshan, Ordos, Shanxi, Taihang, Jilu and Jiaoliao.The evolution of horizontal motions of the blocks in the period of 1995 1996 and 1996 2001 is studied with the GPS data observed in 1995, 1996 and 2001. The results show that the relative motion of the blocks is both inheritable and differential. The general direction of horizontal motion of all blocks in North China is eastward, but some blocks, such as Ordos block were moving westwards in the period of 1995 1996,and the velocity was higher than that in the period of 1996 2001, especially Yinshan Yanshan block. Ordos block showed a tensile separation from Shanxi block, and a left lateral strike slip with Yinshan Yanshan block. This phenomena may be relevant to the preparation of the three earthquakes occurred in the northwest of North China from 1996 to 1999. The study shows that dense and continuous GPS survey can be used in earthquake prediction.