首都圈地壳垂直形变与未来强震活动

据首都圈地区精密水准复测资料,分析了近10年来地壳垂直形变状态与特征。结果表明,北京、天津和河北等平原地区,由于过量开采地下水导致了大空间、大量级的地面沉降,从而无法获得这些区域垂直向构造运动信息。在首都圈地区能够获得构造运动信息的区域主要位于该地区的东北端和西区,东北端为唐山—遵化—兴隆以东和以北的区域,西区指太行山以西的区域。东北端区域整体表现为下降,下降速率为2~ 4 mm/a,但“北升南降”的运动格局没有改变。西区为整体隆升,隆升速率最大近10 m m/a,运动的时空分布从具有“南快北慢”特征的总体上升逐步转变为“北升南降”的有升有降。2001年是西区上述运动性质发生变化的分界线,并由此导致了延怀盆地及其附近的区域出现了比较明显的四象限分布的形变图像。尽管从规模和量级上略小于大同地震前孕震体的变形,但两者的运动图像非常相似,所以该区域可能成为未来强震的孕震地区。

The crustal vertical deformation and the action of future strong earthquake in Capital Circle Area

Crustal vertical deformation and its characteristics in the past decade have been analyzed according to precise re leveling data in the capital circle area.The result indicates that large special and magnitude ground subsidence happened in Beijing,Tianjin,Hebei plain and other regions because of over pumping groundwater,so the tectonic movement information in these areas can't be got and the crustal motion information can be got only in northeastern region and western region of the capital circle area.The northeastern part,i.e.the east and north of Tangshan Zunhua Xinglong,shows subsidence with 2 4mm/a,but the movement situation with rise in the northern part and subsidence in the southern part has not been always changed.The part of western region shows uplift with 10mm/a,the western part is referred to Taihang Mountain.The movement situation has changed from uplifting for the whole region with fast speed in the south and that with slow speed in the north to some uplifting in the north and some subsiding in the south.2001 year is the dividing line that the movement in west region changed.Obvious four quadrant deformation happened in Yanhuai basin and its adjacent areas.Although its scale and magnitude are smaller than that of Datong region before Datong earthquake,their movement patterns are very similar.It could be inferred that strong earthquake might occur in this part in the future.