Earthquake can be defined as a slip of rocks underground on a fault. This results in shaking or by radiating the energy which was caused by slip of the rocks. This can also be understood by the simple language, where there is a sudden stress or changes in the earth, might be volcanic, it might lead to earthquakes. There are some small earthquakes which happen in small areas and these are known as foreshocks. The larger earthquake which happens after foreshocks are known as mainshocks.
