Explain different types of earthquake waves.

Explanation

(i) Body waves: These are generated due to the release of energy at the focus. They move in all directions in all directions travelling through the body of the earth. These are less destructive than the surface waves.
(ii) Surface waves: The body waves interact with the surface rocks and generate new set of waves called surface waves.
These waves move along the surface. These waves are more destruction. The 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. There are two types of body waves. They are called P- and S-waves.
(iii) P-waves: They move faster and are the first to arrive at the surface. These are also called .primary waves.. The P-waves are similar to sound waves. They travel through gaseous, liquid and solid materials.
(iv) S-Waves: S-waves arrive at the surface with some time lag. These are called secondary waves. An important fact about S-waves is that they can travel only through solid materials. This characteristic of the S-waves is quite important. It has helped scientists to understand the structure of the interior of the earth. Reflection causes waves to rebound whereas refraction makes waves move in different directions. The variations in the direction of waves are inferred with the help of their record on seismograph.