The Application Of Wavelet Transform In The Construe Of Survey Data

Impelled by the new technology of Geodesy, modern geodetic research in the geoscience is constantly developing, the task of the Geodesy is not only to describe or monitor the various geodynamic phenomena, but also more importantly, is to explain the mechanism and predict the course of its evolution.Wavelet analysis is the theory of mathematics developed in the mid-1980s, and achieved a wide range of applications in many areas. Firstly, This paper presents the status quo of wavelet analysis applied in survey and mapping, and then the basic Wavelet theory is discussed in detail, especially focusing on the base spline function and the corresponding B-spline wavelet. On this basis, Decompose the 2000-2004 repeat gravity observation data of Hexi area, and compare the result of gravity before and after the calculation, at the same time, the physical meaning of the different bands wavelet decomposition and the corresponding earthquake are discussed, the third-order wavelet decomposition, which reflects the middle crust material changes showed that, in the years of 2000-2001, 2001-2002, 2002-2003 before Minle Ms 6.1 earthquake, the gravity anomalies near the epicentre were very obvious; but the first-order and fourth-order wavelet decompositions, which separately reflect shallow and deep crust material changes show very little response to Minle Ms6.1 earthquake, This may be because Ms 6.1 earthquake occurred in the middle (about 12km deep); the second wavelet decomposition of gravity anomaly in Hexi area consist with the geological structure, which largely reflect the gravity anomaly caused by faults; in the year of 2003-2004 after the earthquake, the first-order, second-order, third-order and forth-order wavelet decomposition of gravity anomaly in Hexi area show little response to Minle Ms 6.1 earthquake., the vertical crustal deformation data decomposition results of Hexi area in the years of 1971-1979,1979-1983 show : the low-order wavelet decomposition results of vertical crustal deformation in Hexi area consist with the geological structure, which show the shortwave mainly reflect activity of the faults; before Qinghai Menyuan Ms6.4 earthquake in 1986,the vertical crustal activity near Menyuan areas is very intensity, and the scope, intensity are extending evidently.