摘要
在对渭河盆地GPS观测资料、流动重力和跨断层形变观测资料精细处理的基础上绘制了相应的时空变化图件,并对其进行了综合分析。结果表明:①陇县—岐山—周至—户县一线既是面应变压缩区,又是重力变化梯度带,还是布格重力异常梯度带,说明这一区域应力场异常变化与深部构造有关。②穿越该区域的陇县—岐山—马召断裂2010年以来断层活动表现为挤压变形特征,逆继承性构造运动显著。③在面应变率压缩区,地壳介质密度增加,重力场呈正向变化,断裂活动表现为挤压变形特征;反之则相反。④岐山-马召断裂2004年7月以后的两次逆继承性构造运动可能是甘肃迭部4.9和岷县6.6地震孕育发生过程中的远场效应。
We selected the gps data since we have the GPS mobile observation network in Shaanxi province, and compared with the mobile gravity and cross-fault deformation observation data, we are aimed to investigate the variation of Weihe basin topography changes and their relationships. With the data of GPS mobile observation network in Shaanxi province during 2001--2010 and 2001--2012, the high-precision horizontal velocity field of Weihe basin processed by the software of GAMIT / GLOBK was obtained. The regional background strain characteristic parameters were calculated according to the velocity and strain theory by least squares collocation method. We have used the software,which is updated by China Institute of Seismology,to process the mobile gravity data of Guanzhong area,we also use some points nearby Weinan to do adjustment calculation to be stable. We have used the cross-fault deformation observation data,which is observed by high preci sion balance level NI002,to do the feet long correction. Based on fine processing on GPS observation data, mobile gravity and cross-fault deforma- tion observation data in Weihe basin, temporal and spatial variation maps are drawn correspond- ingly and further analyzed comprehensively combined with related deep detecting data and other research results. Results are shown mainly in 5 aspects as follows： @ Longxian--Qishan-- Zhouzhi--Huxian area is a surface strain compressed zone, a gravity change gradient belt and a Bouguer gravity anomaly gradient belt, which indicates that the abnormal changes in stress field in the area is related to the deep tectonics. The Moho mutants to uplift over the Erdos block and the high-speed substances in the upper mantle intrude into the lower crust is one of the deep tec- tonic backgrounds of moderate and strong earthquakes in the region. （~） Longxian--Qishan-- Mazhao fault, passing through the above mentioned area, is of significant inverse tectonic move- ment with fault movement characterized in extrusion deformation since 2010. What should been paid more attention to is that the decrease amplitude of Dayuan 2--3, 2010. 7~2012. 3 （a test point） over the fault is as high as 15.19 mm. @ In the surface strain compressed area, the crustal medium density increases and the change of gravity is positive, fault activity is of extrusion de- formation characteristics. Whereas, in the surface strain stretched area, all of the former men- tioned items are of the opposite situations. @ Two reverse tectonic movements occurred in Qis- han--Mazhao fault since July 2004 are probably the far-field effect in the pregnancy and occur- rence process of Diebu M4.9 and Minxian M6.6 earthquakes in Gansu Province. Having been ob- served for more than 20 years, related measuring sections of the Dayuan deformation site display significant reverse tectonic movement characteristics once a relatively big earthquake activity hap- pens. @ GPS surface strain rate, gravity field variation and cross fault deformation are greatly u- niform and correlated in ground deformation changes in western Weihe basin, which is rare and valuable geographic phenomena that may inspire and promote geoscience research in a certain de- gree.
出处
《地震工程学报》
CSCD
北大核心
2014年第2期292-300,共9页
China Earthquake Engineering Journal
基金
地震行业专项(201208009-13)
关键词
渭河盆地
地形变
GPS应变场
重力场变化
布格重力异常
跨断层形变
Weihe basin
crustal deformation
GPS strain field
changes of the gravitationalfield
Bouguer gravity anomalY
eros-fault deformation
作者简介
高好林（1956-），男（汉族），陕西勉县人，高级工程师，曾长期从事流动重力监测、分析预报及相关研究，现从事地震速报．E--mail：ghaolin2005@163．com
