SECONDARY WAVES (S-WAVES)
Topic—Interior of earth
✓ They are recorded second on the seismograph or S-waves are also called as transverse waves or shear waves or distortional waves.
✓They are analogous to water ripples or light waves.
✓ Transverse waves or shear waves mean that the direction of vibrations of the particles in the medium is perpendicular to the direction of propagation of the wave. Hence, they create troughs and crests in the material through which they pass (they distort the medium).
✓ S-waves arrive at the surface after the P-waves.
✓ These waves are of high frequency and possess slightly higher destructive power compared to P-waves.
✓ The trembling on the earth’s surface caused due to these waves is from side to side (horizontal).
✓ S-waves cannot pass through fluids (liquids and gases) as fluids do not support shear stresses.
✓ They travel at varying velocities (proportional to shear strength) through the solid part of the Earth.
