Consider the following statements with reference to Secondary waves (S-Waves) generated during an earthquake:

1. They create troughs and crests in the material through which they pass.

2. The direction of vibrations of S-waves is perpendicular to the wave direction in the vertical plane.

Which of the statements given above is/are correct?

The correct answer is Both 1 and 2.

Key Points

• Secondary waves (S-waves) are a type of seismic body wave generated during earthquakes and travel through the Earth's interior.
• Statement 1 is correct: S-waves create troughs and crests as they move through the material, causing deformation in the medium they propagate through.
• Statement 2 is correct: The direction of vibrations of S-waves is perpendicular to the wave propagation direction, specifically in the vertical or horizontal plane.
• S-waves are shear waves that move the ground up and down or side-to-side relative to the direction of wave propagation.
• Unlike P-waves, S-waves cannot travel through liquids, as liquids do not support shear stress.

Additional Information

• Primary Waves (P-waves):
  • P-waves are the fastest seismic waves and travel through solids, liquids, and gases.
  • They are compressional waves, causing particles to move back and forth in the same direction as wave propagation.
• S-waves and Earthquake Detection:
  • S-waves arrive after P-waves at seismic monitoring stations due to their slower speed.
  • The time difference between the arrival of P-waves and S-waves helps determine the earthquake's epicenter.
• Surface Waves:
  • These waves travel along the Earth's surface and cause the most damage during an earthquake.
  • Examples include Love waves (horizontal movement) and Rayleigh waves (rolling motion).
• Seismic Wave Propagation:
  • Seismic waves are generated at the focus of an earthquake and propagate outward in all directions.
  • The study of seismic waves provides insights into the Earth's internal structure.
• Seismology and Earth's Layers:
  • S-waves' inability to travel through the Earth's outer core indicates that it is liquid.
  • Seismic wave analysis is critical for understanding tectonic activity and geological processes.