关中地区垂直形变场及其动态演化特征

应用关中地区20余年的精密水准资料，用分段线性速率动态平差法进行统一起算基准的拟稳平差计算．得出了197l～1976、1976-1980、1980-1986和1986～1996年度的垂直形变速率图，从动态的观点研究了关中地区地壳垂直形变场的演化特征。研究结果表明：（1）地壳垂直形变场有规律的变化与区域应力-应变场的微动态活动有关，青藏亚板块和华北亚板块对关中地区的构造变形交替起主导作用，并产生了不同形变特征；（2）地壳垂直运动不是线性的。有加速、反向和停顿，长期平均垂直运动速率低于各时段的变化；（3）地壳垂直变化与断裂活动密切相关。垂直形变的逆继承性构造活动时期远小于继承性构造活动时期；（4）西安是一个特殊沉降区。由于过量开采地下水引起地面急剧下降。

Vertical Crust Deformation Field in the Guanzhong Area and Its Dynamic Evolution Characteristics

There have been 4 phases of precise leveling(1971-1976,1976-1980,1980-1986 and 1986-1996) carried out in the Guanzhong area of Shanxi Province so far.We process the 4 phases of data using segmental linear rate dynamic adjustment method,and study the evolution characteristics of vertical crust deformation field in the Guanzhong area from dynamic viewpoint.The results show:(1) the regular change of vertical crust deformation field in the Guanzhong area may be relative to the micro-dynamic activity of regional stress-strain field,which is mainly controlled by the Qinghai-Tibet subplate and North China subplate alternately;(2) the vertical crust movement isn't linear,exists accelerating,reverse and pause,and its average rate for a long time is smaller than that in every phase;(3) the vertical change of the crust deformation is closely relative to the active faults in the area,and the active period of the reverse inherited tectonic movement is much shorter than that of the inherited one;(4) the excessive exploitation of underground water is the main reason for the ground subsidence of Xi'an.