Earthquake Waves

P Waves

• The first kind of body wave is the P wave or primary wave.
• It is the fastest kind of seismic wave, and the first to arrive at a seismic station.
• P waves can move through solid rock and fluids, like water or the liquid layers of the Earth.
• It squishes and stretches the rock it moves through just like sound waves compress and expand the air as they move through it.
• P waves are also known as compressional waves, because they push and pull.
• Particles subjected to a P wave move in the same direction that the wave is moves in; it is the direction that the energy is traveling in, sometimes called the “direction of wave propagation.”

S Waves

• The second type of body wave is the S wave or secondary wave, and is easy to remember because they’re the second wave to arrive after an earthquake.
• An S wave is about 1.7 times slower than a P wave.
• The biggest difference is that S waves cannot move through liquids because S waves only move through solids, seismologists were led to conclude that the Earth’s outer core is a liquid.
• S waves move rock particles up and down, or side-to-side, and are always perpendicular to the direction that the wave is traveling in (the direction of wave propagation).

Love Waves

• One kind of surface wave is called a Love wave, named after British mathematician A. E. H. Love, who worked out the mathematical model for this wave type in 1911.
• Love waves produce entirely horizontal motion. The amplitude is largest at the surface and diminishes with greater depth.

Source: NCERT