During fault ruptures which cause earthquakes, the sudden breakage and movement along the fault can release tremendous amount of energy. Some of this energy is used up in cracking and pulverizing the rock as the two blocks of rock separated by the fault grind past each other. Part of the energy, however, speeds through the rock as seismic waves. This waves can travel for and cause damage at great distances. Once they start, these waves continue through the earth until their energy is used up.

There are two basic types of seismic waves, and they travel at different speeds through earth. The faster p waves and the slower s waves.

Primary or push waves or P waves

Primary Waves

These are longitudinal in nature like sound waves. The velocity of P waves is highest about 5.4 km/s and depends on the density of the rock and resistance to compression. P waves can pass through liquids also.
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