Seismologists specialize in the study of earthquakes and the waves they produce. As an expert in this field, I can explain the characteristics of P and S waves, which are fundamental to understanding how seismic energy travels through the Earth. P waves, also known as primary waves, are the fastest moving seismic waves. They are compressional waves, which means they cause particles in the material they pass through to move in the same direction as the wave's energy. This movement is similar to how sound travels through the air. P waves can travel through solids, liquids, and gases, but they cannot travel through liquids alone. S waves, or secondary waves, are slower than P waves and are shear waves. They move the particles of the material in a direction perpendicular to the direction of the wave's energy. S waves can only travel through solids; they cannot propagate through liquids or gases because these states of matter do not support shear stress. In summary, P waves are characterized by their ability to compress and decompress materials as they travel, and they can move through all states of matter. S waves, on the other hand, are characterized by their side-to-side or elliptical motion and can only move through solids. read more >>

P Waves are compressional which means they move through (compress) a solid or liquid by pushing or pulling similar to the way sound travels through the air. The particles of the material a P Wave pushes through move in the direction of the P wave's energy. This is called the direction of wave propagation.read more >>