Question

Which one of the following options is the CORRECT sequence of seismic waves in order of arrival time recorded on a seismogram after an earthquake?

• A. P-waves, S-waves, Rayleigh waves, Love waves
• B. P-waves, Rayleigh waves, S-waves, Love waves
• C. S-waves, P-waves, Love waves, Rayleigh waves
• D. P-waves, S-waves, Love waves, Rayleigh waves

Answer 1

The Correct Option is D

Seismic waves generated by an earthquake are of different types. These waves travel through the Earth's interior and surface and are detected by seismographs. Understanding the types and characteristics of seismic waves can help in predicting their arrival times on a seismogram.

1. P-waves (Primary Waves): These are the fastest seismic waves and hence, the first to be recorded on a seismogram. They travel through both solid and liquid layers of the Earth.
   • Speed: Highest among all seismic waves.
   • Motion: Compressional, similar to sound waves, causing particles to move in the direction of wave propagation.
2. S-waves (Secondary Waves): These are slower than P-waves and are recorded second on a seismogram. They travel only through solids and not through liquids.
   • Speed: Slower than P-waves.
   • Motion: Shear, causing particles to move perpendicular to the direction of wave propagation.
3. Love Waves: These are surface waves and are typically the third to arrive. Love waves cause horizontal shifting of the Earth during an earthquake.
   • Motion: Horizontal shearing motion of the ground.
4. Rayleigh Waves: These are also surface waves and typically arrive last on a seismogram. They move in an elliptical motion, similar to waves on water, affecting both vertical and horizontal ground motion.
   • Motion: Rolling motion similar to ocean waves, causing both vertical and horizontal ground movement.

The correct sequence of arrival of seismic waves on a seismogram is as follows:

• P-waves
• S-waves
• Love waves
• Rayleigh waves

Therefore, the correct answer is: P-waves, S-waves, Love waves, Rayleigh waves.