1. In a seismograph, P waves are recorded earlier than S waves.
2. In P waves, the individual particles vibrate to and fro in the direction of wave propagation whereas in S waves, the particles vibrate up and down at right angles to the direction of wave propagation.

P Waves vs. S Waves

In a seismograph, P waves (Primary waves) are recorded earlier than S waves (Secondary waves) because P waves travel faster through the Earth’s interior than S waves. This is due to the fact that P waves are compressional waves that can travel through both solid and liquid materials, while S waves are shear waves that can only travel through solid materials.

Characteristics of P Waves and S Waves

In P waves, the individual particles vibrate to and fro in the direction of wave propagation, which means they move back and forth along the same direction as the wave is traveling. In S waves, the particles vibrate up and down at right angles to the direction of wave propagation, which means they move perpendicular to the direction in which the wave is traveling. This difference in particle motion is what distinguishes P waves from S waves and contributes to their different speeds and abilities to travel through various materials.