The frequency-wavenumber domain in which the independent variables are frequency (f) and wavenumber (k,) the result of a 2D Fourier transform of a seismic record or seismic section; f-k space. Seismic data analysis sometimes involves f-k plots (see Figure F-11) in which energy density within a given time interval is contoured on a frequency-versus-wavenumber basis. Used to examine the direction and apparent velocity of seismic waves and in velocity-filter design.
FIG. F-11. f,k plot. (a) The region passed by array, frequency, and velocity filters is cross-hatched. Radial lines through the origin represent constant apparent velocity Va (Va=f/k=ω/κ). (b) Data beyond the Nyquist wavenumber fN (determined by discrete spatial sampling) wraps around (aliases) and may get mixed up with the signal. In wraparound, data to the right of +kN continues rightward from –kN, where KN is the Nyquist wavenumber.