Erroneous Phase Velocities from Frequency-Wavenumber Spectral Sections

Two-dimensional cross-sections of finite frequency-wavenumber spectra can easily be misinterpreted, since leakage of energy occurs along lines of constant wavenumber. In particular, the signal phase velocity determined from measurements on cross-sections normal to the frequency axis can be incorrect. We discuss an algorithm which corrects this situation. Examples using real and synthetic data are given.