渭河盆地现今地壳水平形变特征及区域构造活动性
Research on Present Crustal Horizontal Deformation Feature of Weihe Basin and Its Tectonic Activity
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摘要: 根据渭河盆地地质构造的特点,建立了二维有限元模型,并基于渭河盆地2001~2007年GPS观测成果,数值模拟获得了渭河盆地现今地壳应力应变场特征,结合区域近期地震活动性特点,探讨了地壳形变特征与地震活动性的关系。结果表明,渭河盆地现今构造应力场仍以NNW-SSE向拉张应力为主;盆地最大剪应变率高值区与盆地现代小地震条带有很好的空间对应关系;泾阳-咸阳-西安-临潼-三原地区属于渭河盆地内地壳薄弱带,易于盆地伸展和地震孕育。Abstract: In this paper,two-dimensional finite model of elastic mechanics is established according to the geological structure features of Weihe Basin.And the author obtains the stress and strain characteristics by the 2001~2007 GPS data in this region.In the end combine with the characteristic of recently seismic activity in Weihe basin,The relation between crustal deformation characteristics and the seismic activity is also discussed.The results show that current tectonic stress field of this basin presents tensile stress with NNW-SSE direction.The spatial distribution of maximum shear strain rate in Weihe basin has a very good correlation with small modern seismic belt.The region of Jingyang-Xianyang-Xi'an-Lintong-Sanyuan belongs to the weak zone in the crust of Weihe Basin which is apt to basin extension and earthquake preparation.