Consider the following statements : In a seismograph, P waves are recorded earlier than S waves. 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. Which of the statements given above is/are correct?

The correct answer is (c). Both statements 1 and 2 are correct.

P waves are compressional waves, which means that

the particles of the medium through which they travel vibrate in the direction of the wave’s propagation. S waves are shear waves, which means that the particles of the medium through which they travel vibrate perpendicular to the direction of the wave’s propagation.

P waves are always recorded earlier than S waves on a seismograph because they travel faster. P waves travel at about 7 km/s, while S waves travel at about 4 km/s. This is because P waves are compressional waves, which means that they can travel through solids, liquids, and gases. S waves, on the other hand, are shear waves, which means that they can only travel through solids.

Therefore, when an earthquake occurs, P waves will reach a seismograph first, followed by S waves.