采用拟稳平差方法对1992—2011年陕西关中重力测网流动观测资料进行平差计算,获得各期高精度重力值,利用Kriging插值算法获得差分及累积重力场变化图像,结合1998年1月5日泾阳MS4.8地震及2009年11月5日高陵MS4.4地震,分析2次地震前后重力场及重力点值时序变化特征。结果 表明:(1)2次地震前后都有较明显的重力异常变化,变化过程表现为正向―负向―正向重力变化,符合地震扩容模式;(2)2次地震的发生与渭河断裂及泾阳—渭南断裂构造活动有关,震中位置处于重力等值线零值线及拐弯处,但2次地震前重力累积变化不明显;(3)关中西部重力测点在2次地震前后重力值变化显著,关中东部重力点值变化不明显,震中附近的测点在泾阳地震前后变化明显,在高陵地震前后变化不明显。
Using the quasi stable adjustment method,we estimate and calculate the data of Shaanxi Guanzhong gravity network,and obtain the value of the high precision gravity. Using Kriging interpolation algorithm,we obtain the differential and cumulative variation of gravity field images.Combined with 1998 January 5,Jingyang MS4.8 earthquake and 2009 November 5,Gaoling MS4.4,we analyzed the characteristics of the gravity field and the time series variation of gravity before and after two earthquakes. The results show that:(1)There are obvious gravity anomalies before and after two earthquakes,and the change process is the positive-negative-positive change,to meet the expansion mode;(2)The two earthquakes is related with tectonic activities of the Weihe Fault and Jingyang-Weinan Fault,the location of the epicenter is nearly in gravity zero line and corner of isoline,however,the earthquake gravity cumulative change is not obvious before two earthquakes;(3)The gravity change is obvious in western of Guanzhong before and after two earthquakes,however,in eastern of Guanzhong,the gravity values change is not obvious. The gravity points near the epicenter change is more obvious before and after the Jingyang earthquake than that of Gaoling earthquake.
