I. Introduction
Seismic signal analysis based on the Fourier transform (FT) is more challenging because of its limitations. The Fourier method cannot provide simultaneous time and frequency localizations and is not useful for analyzing time–varying nonstationary signals. Time–frequency representation unfolds this temporal information and maps a time series into 2-D quantity of time and frequency with effective characterization of the time–frequency image. The short-time FT (STFT) overcomes the limitations of FT to some extent. In STFT, the signal is divided into small enough segments, where these segments of the signal are assumed to be stationary. As STFT involves window function, the time and frequency resolutions are determined by the width of the analysis window, which is selected once for the entire analysis; therefore, the time–frequency resolution is constant [1].