seismic wave

A wave of energy that travels through the earth or along its surface, generated by an earthquake, an explosion, or a volcanic eruption. Body waves travel through the earth's interior: P-waves (primary, compressional — the first to arrive, pushing and pulling the rock like a slinky) and S-waves (secondary, shear — slower, moving the rock side to side). Surface waves travel along the surface and cause the most damage: Love waves shake horizontally, and Rayleigh waves roll the ground in an elliptical motion, like ocean swells passing through stone. The earth has a grammar of motion, and seismic waves are its sentences.