Shear Wave
A shear wave (S wave) is an elastic body wave in which particles oscillate perpendicular to the direction in which the wave propagates. Shear waves travel more slowly than compressional waves (P waves) and cannot travel through fluids because fluids do not support shear. Interpretation of S waves can allow determination of rock properties such as fracture density and orientation, Poisson's ratio, and rock type by cross-plotting P-wave and S-wave velocities and by other techniques.
