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Three Seismic Waves

Seismicwaves can be generated by the movement of earth that is earthquake or explosion. The variable velocity can be moving with the surface and internal depending on the material traveled. Seismic waves can be discerned using the layers of the earth such as mantle, crust inner and outer core. Earthquake can be produced by both transverse waves (S-waves) and longitudinal waves (P-waves) are said to be seismic waves.Let us learn about three seismic waves.

Three Classifications of Seismic Waves

The seismic waves can be classified into three waves,

  • P-waves
  • S-waves
  • Surface waves


The body waves can be classified into two waves.

        The inner layers of the earth are the main part of the seismic waves occurs.  The density and velocity changes of the inner layers can be transmitted or reflected and it obeys Snell’s Law.

Snell’s law states that:

n = sin i/ sin r


  • i is the angle of incidence
  • r is the refraction
  • n is the refractive index

Demonstration of Three Seismic Waves




 It is the primary waves of another three seismic waves. Otherwise P-wave is known as push-pull and the fastest kind of seismic waves. It can push and pull the materials which can travel through solids and fluids when it moves through it. It is very similar to sound waves. It involves refraction and compression of the material in which it is alongthe direction of propagation of wave. It is said to be longitudinal wave.




 This wave is a second of the seismic waves. It is helpful to feel the earthquake. It is otherwise called as shear or secondary waves. The wavemoving through up and down or side-to-side, it involves the rotation and shearing of the material. The movement of the wave can be transversewith moving particles and perpendicular to the ray. The outer core is liquid in earth and S-wave cannot travel through it. It cannot be observed on the far side of the earth from an earthquake.

Surface Waves:

This is the last of the three seismic waves. It can oscillate the surface of the planet with ripples of water. It consists of Rayleigh’s waves and Love waves.



It is called as ground roll. It rolls like the oceanic waves propagate.The larger is the displacements and decreases downwards with dispersionof waves and velocity can be varying with wavelength. In earthquake, shaking can be mainly due to Rayleigh waves.

Love Waves:


The fastest surface wave is the love waves. This wave is parallel to the ground surface travelling in transverse motion. It moves up the ground in side-to-side motion similarly like the S-waves.