Earthquake Waves

Earthquake in simple words is shaking of the earth. It is a natural event. It is caused due to release of energy, which generates waves that travel in all directions. 

• The point where the energy is released is called the focus of an earthquake, alternatively, it is called the hypocentre. 
• The energy waves travelling in different directions reach the surface. The point on the surface, nearest to the focus, is called epicentre.
• All natural earthquakes take place in the lithosphere or earth consisting of solid rocks. An instrument called ‘seismograph’ records the waves reaching the surface.
• The earthquake events are scaled either according to the magnitude or intensity of the shock. The magnitude scale is known as the Richter scale.

Earthquake Waves: There are Three types of Earthquake Waves. They are called P-waves, S-waves and surface waves. 

1. P-waves or ‘primary waves’ move faster and are the first to arrive at the surface. They travel through gaseous, liquid and solid materials. 
2. S-waves or secondary waves arrive at the surface with some time lag.  
3. Surface waves are the last to report on seismograph. These waves are more destructive. They cause displacement of rocks, and hence, the collapse of structures occurs.

Check Geography Notes at Geography of World and India or Notes section of INDIA GK Mobile App.