Abstract

In recent years, the method of wavelet transform has been applied and developed strongly in the geodesy field in many countries around the world. Some study results have pointed out dominant advantages of this method in reducing noise, extracting initial disturbance signals, analyzing GNSS measurement data in time series, building geoid model and in studying the deformation of the Earth’s crust. This paper presents the theoretical basis of the wavelet transformation method in cal-culating the deformation quantities in Northern region of Vietnam, which based on the velocity field interpolation results, according to the 4-cycle GNSS measurement data (2012-2015). Calculated results have shown that the modern tectonic activity of the crust in these areas is very weak and it only concentrates on the fault area Lai Chau - Dien Bien with the maximum rotation rate: 4.0x10-8 rad/year, maximum strain rate: 0.84x10-8 /year, maximum shear rate: 8.0x10-8 /year and maximum dilatation rate: 4.5x10-8 /year. This result is quite consistent with the study result concerning the activ- ities of fractures in Northern regions which had been published ago.