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.

Secondary or shake waves or S waves

Secondary Waves

These are transverse in nature like light waves. The velocity of S waves is about 3.3 km/s. The velocity of S waves depends upon density of the rock and resistance to distortion. The S waves cannot pass through liquids.

Surface waves

When the P-waves and S-waves travel on the surface, they are known as surface waves

L waves and Rayleig Waves

These are also transverse in nature like S waves. The velocity of S waves is about 3.0 km/s. L waves are formed due to dashing of P and S waves against the solid crust of the earth. These are the waves, which we feel in the form of earthquake. These waves are responsible for the destruction of the life and property. Height of L waves is about 30cm and distance between two successive crests is about 10 m. and increase in their amplitude beyond only 1/16 of an inch is capable of causing lot of destruction. Due to high velocity of these waves, the civil engineering structures vibrate and a typical sound due to passage of energy is heard.