Here, we make the characters move from side to side.
Motion is parallel to the direction of wave propagation.
These are like primary or compressional waves which move through the depths of the Earth when earthquakes occur. Here, we make the characters move up and down, with each character one-eighth of a phase behind the previous one. The motion is perpendicular to the direction of wave propagation. These are like secondary or shear waves which, like primary waves, propagate through the Earth after they are generated by earthquakes. Here, we make the characters move in circles with the with the upper component of the motion in the same direction as that of wave propagation.