1. n. [Geophysics]

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

v_a = v cos θ,

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

See: receiver,  velocity,  wave