Toward Improved Method of Estimating attenuation, Phase and Group Velocity of Surface Waves observed on Shallow Seismic Records

In the estimate of dispersion with the help of wavelet analysis much emphasis has been put on the extraction of the group velocity using the modulus of the wavelet transform. In the present contribution we propose a method based on the analysis of the deformation of the full wavelet transforms (modulus and phase) of the seismic traces at the dierent receiver stations. The analysis is based on an initial parameterization of t the phase velocity (the group velocity) and the attenuation coecient which are then determined through the minimization of a properly dened cost function. Depending on the nature of the analyzed signals, dierent types of cost functions are dened. The design of these cost functions is made in such a way to reduce the eect of non-coherent arrivals on the overall optimization results. The method is tested on both numerical and experimental data. 1 CONTINUOUS WAVELET TRANSFORM De nition of the wavelet transform of a signal s 2 L2(R) Wgs(b; a) = +1