Earthquakes Can Be classified into different categories on the basis of region where it  occurs and the geological make-up of that region as :

(i)     Tectonic earthquake: most commonly it occurs when rocks in the earth's crust break due to geological forces created by movement of tectonic plates.

(ii)   Volcanic earthquake: it occurs in conjunction with volcanic activity.

(iii) Collapse earthquake: these are the small earthquakes which occur in underground mines and caverns.

(iv) Explosion earthquake: these mainly occur due to the explosion of nuclear and chemical devices.