Seismologists have long understood that the type of seismic wave that typically causes the most damage during an earthquake is the S wave. P waves, or primary waves, are the first to be felt when an earthquake occurs because they travel through the Earth's crust at a faster speed than S waves. However, P waves are generally less destructive because they are more like sound waves, compressing materials as they pass through. In contrast, S waves are much slower and arrive after P waves. They are responsible for the more violent shaking associated with earthquakes. S waves are shear waves, which means they move the ground side to side or up and down, causing significant stress on structures and leading to more damage. This is why they are often associated with the most destructive effects of an earthquake. To summarize, while P waves are felt first and can alert people to an impending earthquake, it is the S waves that are more likely to cause the most damage. read more >>

P waves travel fastest and are generally felt first. They usually cause very little damage. B: S, or secondary waves or shear waves, are seismic body waves that shake the ground back and forth perpendicular to the direction the wave is moving.read more >>