Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. Seismograph is used to detect and record earthquakes.
Two types of seismic waves are:
1. BODY WAVES - travel through the earth's inner layers.These are higher frequency than surface waves.
Kinds of Body Waves:
a. P WAVES (primary wave) - this is known as compressional waves because of pushing and pulling movement. This is the fastest seismic wave. This is first to arrive than the S waves.
b. S WAVES (secondary wave) - the second wave in an earthquake. It is slower than P waves. S waves move rock particles up and down, or side-to-side--perpendicular to the direction that the wave is traveling in.
2. SURFACE WAVES - travel through the crust, with lower frequency than body waves. This is more destructive wave associated to earhquake. It arrives after body waves.
Kinds of Surface Waves:
1. LOVE WAVES- named after A.E.H. Love, a British mathematician who worked out the mathematical model for this kind of wave in 1911. It's the fastest surface wave and moves the ground from side-to-side. Confined to the surface of the crust, Love waves produce entirely horizontal motion.
2. RAYLEIGH WAVES - named for John William Strutt, Lord Rayleigh, who mathematically predicted the existence of this kind of wave in 1885. A Rayleigh wave rolls along the ground just like a wave rolls across a lake or an ocean. Because it rolls, it moves the ground up and down, and side-to-side in the same direction that the wave is moving. Most of the shaking felt from an earthquake is due to the Rayleigh wave, which can be much larger than the other waves.
