北京地区近十年应变场变化特征

CHARACTERISTICS OF STRAIN FIELD VARIATION IN BEIJING AREA

北京地区1995～2005年不同时段的应变率揭示出:1995～1996年和1996～1999年的最大剪应变率较大,与1996～1999年阴山燕山南缘构造带、张家口渤海构造带的地震相对活跃的时段基本一致;1999～2001年和2001～2004年为应变率相对较小的时段,而这两个构造带的地震也相对平静;北京地区各时段的最大剪应变率等值线的最大值都在10-7/a以上,表明该区为构造蠕变较强烈的地段。

The strain rates in the different period during 1995 -2005 in Beijing area indicate that the maximal shear strain rates, in the periods during 1995 - 1996 and 1996 - 1999, were larger than those in other periods and basically consistent with the period during 1996 -1999 in which the seismic activity in Yinshan-Yanshan southern margin and Zhangjiakou-Bohai tectonic zones was high. In the periods during 1999 -2001 and 2001 -2004, the strain rates were relatively small while the seismic activity of this two tectonic zones were relatively low also. In Beijing area all of the maxima of the maximal shear strain rate in above every period reached over 10^7/a, it indicates that this area is a segment of strong tectonic creep.