利用GPS数据探讨鄂尔多斯地块西南缘地壳动态演化特征

利用GPS大地测量数据，借助最小二乘配置方法构建位移与应变间的偏导关系，探讨了鄂尔多斯地块西南缘地震空区近10年尺度地壳运动速度场、应变场的动态演化特征，分析了研究区域较少发生地震的成因。结果表明：地壳物质流在阿拉善地块、鄂尔多斯地块与西秦岭构造区的复杂地质构造交汇处，地壳内部物质流加速东移，板块间应力积累特征不显著；六盘山断裂、陇县—宝鸡断裂带以西，显示了EW向或NE向的压应变，而沿断裂走向则以拉应变为主，表明西侧地壳物质沿鄂尔多斯地块西南缘东迁顺时针旋转的运动状态；在岐山至扶风一带，出现了面膨胀的特征，释放了地壳内部的压应力，但构造内部运动并无闭锁现象出现，这可能降低了研究区域地震孕育与发生的风险。

Discussion on dynamic evolution characteristics of the crust in the southwestern margin of Ordos block based on GPS data

Based on GPS geodetic data and the least square collocation method, the partial derivative relationship between displacement and strain is constructed, and the dynamic evolution characteristics of crustal movement velocity field and strain field in recent 10 years in the seismic gap of the southwest margin of Ordos block are discussed. The causes of less earthquakes in the study area are analyzed. The results show that the crustal material flow is in the Alxa block and Ordos block at the intersection of the complex geological structure with the West Qinling tectonic area, the material flow in the crust accelerates eastward, and the stress accumulation characteristics between plates are not significant; to the west of Liupanshan fault and Longxian-Baoji fault zone, the compressive strain shows East-West or northeast direction, while the tensile strain is dominant along the fault strike, indicating that the crustal material in the west moves eastward and rotates clockwise along the southwest edge of Ordos block. In the area from Qishan to Fufeng, the characteristics of surface expansion appear, releasing the compressive stress in the crust, and there is no locking phenomenon in the internal movement of the structure, which may reduce the risk of earthquake preparation and occurrence in the study area.