Resolution equivalence of dispersion-imaging methods for noise-free high-frequency surface-wave data

A key step in high-frequency surface-wave methods is to acquire the dispersion properties of surface waves. To pick dispersion curves, surface-wave data is required to be transformed from the time-space (t-x) domain to the frequency-phase velocity (f-v) domain. In constructing accurate multi-mode dispersion curves, it is necessary to generate a reliable and high-resolution image of dispersion energy in the f-v domain. At present, there are five methods available for imaging dispersion energy: the τ-p transformation, the f-k transformation, the phase shift, the frequency decomposition and slant stacking, and the high-resolution linear Radon transformation. Among them, resolution of the high-resolution linear Radon transformation is the highest. We proposed a processing step to enhance resolution of the other four methods. Resolution of the four enhanced methods and high-resolution linear Radon transformation is compared by imaging dispersion energy of the same synthetic data. As a result, the four enhanced methods generated dispersion images with the same resolution, which revealed that the resolution of the five dispersion-imaging methods is essentially equivalent for noise-free data.