In P or compressional waves, the vibration of the rock is in the direction of propagation. In S or shear waves, rock oscillates perpendicular to the direction of wave propagation. In rock, S waves generally travel about 60% the speed of P waves.

Location: 28°25.41' N 77°05.55' E, Gurugram, India, by VU2UUU, Kaustav Saha