Wavelet spectrogram analysis of surface wave (WSASW) method has been introduced and recently implemented to improve the field measurement of shear wave velocity and damping ration on soil sites. This method improves a common used signal prcossing tools, e.g., Fourier analysis, for attenuation analysis which fail to identifiy when certain characteristic features occur in a waveform. The time-frequency character of wavelet trancforms allows increased flexibility as both traditional time and frequency domain system identification approaches can be exploited to examine non-linear and non-stationary seismic events that are in essence obscured by traditional spectral approaches. This paper presents application of wavelet spectrogram analysis of surface wave method for simultaneous shear wave velocity, damping ratio and long-term settelement calculation on soft caly. Soil model is treated as an elastic material of viscoelastic property. The calculated elastic settlement form shear wave velocity and its corresponding shear modulus, and equivalent formula. Comparisons to traditional methods of settlement preditictions were made and the viscoelastic formula has shown better agreement to observed settlement.