The value of the square root of the sum of the squares of the velocity values divided by the number of values, symbolized by v_{rms}. The root-mean-square velocity is that of a wave through subsurface layers of different interval velocity along a specific raypath, and is typically several percent higher than the average velocity. The stacking velocity and the root-mean-square velocity approach equality when source-receiveroffset approaches zero and layers are horizontal and isotropic.