Using transfer function for estimating dissipative properties of soils from surface-wave data
The quality factor (or damping ratio) can be estimated by analysing the spatial attenuation of surface-wave data. However, because of the link between geometrical and material dispersion, a coupled analysis of dispersion and attenuation curves is preferable. Using a transfer-function approach, it is possible to estimate the dispersion and attenuation curves simultaneously, provided the seismic source is known. A formulation based on the deconvolution of seismic traces is used to extend the transfer-function approach to ordinary seismic gathers in which the source wavelet is not known. The measured transfer function is used in a regression analysis to obtain estimates of the complex wavenumbers, which, in the framework of viscoelasticity, contain all the information relating to phase velocity and attenuation of surface waves for a layered medium. Application of this procedure to experimental data leads to results consistent with those obtained using conventional techniques (e.g. f–k analysis and amplitude regression).