P-wave

P-waves are longitudinal: the material vibrates back and forth in the direction the wave travels. They can pass through both solids and liquids, but their speed changes when they enter a different material. A change in speed can bend their path, a process called refraction.

P-waves are longitudinal waves: the rock vibrates back and forth along the direction in which the wave travels. They travel through solids and liquids and arrive before the slower S-waves. S-waves are transverse: the rock vibrates across the direction of travel.