The literal meaning of ‘earthquake’ is shaking or trembling of the earth’s crust. Here a few definitions revealing the nature and cause of an earthquake are being given to make this phenomenon easily understandable.

According to Worcester, “an earthquake is a vibration or oscillation of the surface of the earth caused by a transient disturbance of the elastic or gravitational equilibrium of the rocks at or beneath the surface”.

Any major disturbance in the arrangement of rocks produces vibrations which spread out in all directions from the source of disturbance.

In fact, an earthquake presents the passage of such vibrations which results in the shaking of the crustal surface of the earth.


An earthquake can also be defined as a shaking of the ground surface ranging from a very mild tremor to a wild motion capable of shaking buildings apart.

“Earthquakes are vibrations of the earth that occur when the accumulating strain of slow crustal deformation is suddenly released by displacement along a fault. It is worthwhile to remember that an earthquake does not cause displacement of rocks.

It is important to note that earthquakes signify the release of energy caused by the movement of crustal blocks past one another. In other words, earthquakes can be defined as a convulsion of the earth’s crust due to the release of accumulated stress as a result of faults in strata or volcanic action.

Stresses in the earth’s crust may be caused in various ways to be discussed later while describing the causes of earthquakes. As a matter of fact, earthquakes are the most prominent evidence of the present day diastrophism.