华北近十年来水平运动动态与地震活动危险区的讨论
DISCUSSION ON THE TREND OF HORIZONTAL MOVEMENT OF NORTH CHINA IN CURRENT DECADE AND THE ACTIVE RISK AREA OF EARTHQUAKE
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摘要: 根据华北地区1999和2001年两期高精度GPS观测结果,通过与1992、1995、1996和1999年这几期资料的比较,发现近两年的运动与前有所不同,主要表现为:1阴山单元和鄂尔多斯单元之间显示为压性运动的性质,但比较微弱;它们之间的边界带上似乎有左旋走滑运动,但从整体上看并不显著。2晋冀鲁单元和燕山单元的整体活动性不如以前,各单元内部存在着较明显的差异运动,燕山单元和晋冀鲁单元的北部存在着比较显著的东西向挤压,北京地区则表现为南北向挤压。3晋冀鲁单元南部与胶辽鲁苏单元的南部的趋势活动呈张性,优势运动方向为东南。这样的结果可能表明:华北目前存在着应力扰动行为,大同与天津之间的区域是受其影响最大的地区,该区有可能成为未来几年中强地震活动的一个主体地区。Abstract: compared the GPS data observed in 1999 and 2001 with the data observde in 1992, 1995, 1996 and 1999, the crustal movement is found different from its previous character, which behaves as the following:① there is a weaker compressive motion with left-lateral strike slip between Yinshan unit and Ordos unit, but not obvious;② the motion of Jinjilu unit and Yanshan unit are not the same as before, but there is obvious differential movement in the interior of the units, which is EW extrusion in northern part of the units, and NS extrusion in Beijing area;③ the deformation of the southern part of Jinjilu unit and Jiaoliaolu unit is extensional with a dominant direction of SE.These results show that there is a stress disturbing in North China currently, and the area between Datong and Tianjin is the most influenced region, which would be an main zone of medium and strong earthquakes in a few years.