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apparent velocity

1. n. [Geophysics]

In geophysics, the velocity of a wavefront in a certain direction, typically measured along a line of receivers and symbolized by va. Apparent velocity and velocity are related by the cosine of the angle at which the wavefront approaches the receivers:

va = v cos θ,

where
va = apparent velocity
v = velocity of wavefront
θ = angle at which a wavefront approaches the geophone array.