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(Note that during a strong earthquake, ground shaking consists of a combination of various kinds of seismic waves.) A. As illustrated by a slinky, P waves are compressional waves that alternately compress and expand the material through which they pass. B. The back-and-forth motion produced as compressional waves travel along the surface can cause the ground to buckle and fracture, and may cause power lines to break. C. S waves cause material to oscillate at right angles to the direction of wave motion. D. Because S waves can travel in any plane, they produce up-and-down and sideways shaking of the ground. |
