【摘要】 采用富里叶分析法，从中国西部地区20多年的地壳垂直形变资料中提取区域性趋势倾斜信息，并对宁夏海原5．7级地震、四川西部道孚6．9级地震和青海门源6．4级地震震区近场垂直形变场的区域性倾斜信息进行厂分离和提取，推导出厂用富里叶级数表示的梯度公式。通过研究倾斜梯度矢量在地震过程中的变化特征，得到如下结论：（1）垂直形变信息中区域性倾斜信息表现出明显的有序性和相似性；（2）同一区域，发生了地震的时间段区域性趋势倾斜梯度矢量位于同一象限或处于对角象限；（3）中国西部地区地壳主要受印度板块向东北方向的挤压作用，受太平洋板块向西的挤压不明显。更多还原

【Abstract】 In this paper, The Fourier-ancvalysis method is used to seperate the tilt information fromthe vertical deformation data of both West China in 20-odd years and the epicentral areas offollowing earthquakes: Daofu earthquake (M6. 9),Haiyan earthquake (M5. 7) and Menyuanearthquake (M6. 9), and the tilt gradient formula expressed by Fourier series is concluded.The tilt gradient vectors in different period for above earthquakes are calculated with thisformula. The results show: (1)The direction of the tilt gradient vectors is of obvious orderand self-resemblance ; (2) In a same area, the tilt gradient vectors during the period whichthe earthquake occurred are located in the same quadrant or the opposite ; (3) The crust inWest China is controlled primarily by the eastnorth compression from the india Plate, andwest compression from the Pacific Plate is a secondary force.Descriptors: Crustal tilt ;Deformation field investigation; Vertical deformation analysis ; Gradient更多还原