The earthquake waves based on their mode of traveling and velocity are broadly classified into three types. They are,
Primary (P) waves
Secondary ( *)waves
Surface (L) waves
1. Primary (P) waves: These are also known as Push waves or waves of compression. The particles vibrate in the direction of the movement of the wave, similar to a sound wave. They can travel through solid, liquid and gases. The velocity varies from 5.5 to 13 km per second depending on the medium of their travel they are the first to be recorded in the epicenter by the seismograph.
*2. Secondary ( ) waves:* They are recorded on a seismogram after the P) waves. These are also called traverse or shake waves ( ). These are distortional waves as the particles vibrate at right angles to the direction of the movement of the waves. The velocity of the secondary waves varies form 3 to 7 kms per second. They can travel through the interior and outer layer of the earth but cannot be transmitted by liquids.
3. Surface waves: These are also described as Long waves (L). The ‘L’ waves travel along the surface of the earth and are recorded after ‘P’ and ‘*’ waves. Their speed is 4 kms. The surface waves are most destructive as they vibrate much.
