3.1.2. Surface Waves
This design approach will focus on surface waves, as opposed to body waves, because they propagate solely through the crust of the Earth. Because surface waves propagate through the crust makes them most harmful to man-made structures.
Surface waves are usually secondary to body waves in that they arrive later. In some cases, an earthquake’s magnitude can be calculated prior to it hitting a region thanks to the speed of the body waves. However, knowing how powerful an earthquake will be moments, or even hours before it arrives is not very helpful in preparing for its possible devastation.
3.1.3. Love Waves
Love waves are the fastest of surface waves and move in a purely horizontal direction. They move side to side while propagating horizontally. Figure 3.3 distinguishes the purely horizontal motion created by the love wave.