In the geosciences, especially seismic data analysis, these plots also called f–k plot, in which energy density within a given time interval is contoured on a frequency-versus-wavenumber basis.
They are used to examine the direction and apparent velocity of seismic waves and in velocity filter design.
of a sinusoidal wave is: Using the wavenumber (
ω = 2 π ν
) notation, the previous equation can be rewritten as On the other hand, the group velocity is equal to the slope of the wavenumber–frequency diagram: Analyzing such relationships in detail often yields information on the physical properties of the medium, such as density, composition, etc.