Question

What are the three types of Seismic waves?

Answer 1

Seismic waves:

• Seismic waves are created by the abrupt movement of elements within the Earth, such as fault slip during an earthquake.
• Seismic waves can be caused by volcanic eruptions, explosions, landslides, avalanches, and even flowing rivers.

Types of Seismic waves:

• Primary waves:
  • Primary waves (P-waves) are compressional waves that travel in a straight line.
  • P-waves are pressure waves that move quicker through the ground than other waves, arriving first to seismograph stations, thus the term "Primary."
  • These waves may move through any substance, including fluids, at roughly 1.7 times the speed of S-waves.
  • They assume the shape of sound waves in air and hence travel at the speed of sound.

• Secondary waves:
  • Secondary waves (S-waves) are transversely oriented shear waves.
  • S-waves arrive at seismograph stations after the faster-moving P-waves and displace the ground perpendicular to the propagation direction.
  • The surface features of the wave might vary depending on its propagational direction; for example, in the case of horizontally polarised S waves, the ground moves alternately to one side and then the other.
  • Because fluids (liquids and gases) do not support shear forces, S-waves can only move through solids.

• Surface waves:
  • A surface wave is a mechanical wave that propagates at the interface of two different mediums in physics.
  • Gravity waves on the surface of liquids, such as ocean waves, are a frequent example.
  • Gravity waves may also arise within liquids, for as at the interface of two fluids of differing densities.