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?
1 only
2 only
Both 1 and 2
Neither 1 nor 2
Correct Answer: Option (c)
P-waves move faster and are the first to arrive at the surface. These are also called ‘primary waves. The P waves are similar to sound waves. They travel through gaseous, liquid and solid materials. S-waves arrive at the surface with some time lag. These are called secondary waves. Hence, statement 1 is correct.
The P-waves are longitudinal waves, so P-wave particles vibrate parallel to the direction of the wave. But S-waves are transverse waves, so S-wave particles vibrate perpendicular to the wave direction in the vertical plane. Hence, statement 2 is correct,
