Earthquakes usually occur along a fault line. What is a fault? It is a

fracture in the earth's rocky outer shell where portions of rock slide

past each other. The shaking of an earthquake is the result of the stress

on large blocks on that lie along a fault thus making it strain or bend.

There are 3 types of faults in motion. They are the strike-slip fault,

normal fault and the thrust fault. A displacement of faults of any type

could be the accumulation of smaller displacements of individual

earthquakes.

Different faults is connected to the force of an earthquake. Normal

faults usually cause small earthquakes while thrust faults and strike-slip

faults usually cause large earthquakes.

Movement of plates also cause earthquakes. It allows build-up of

elastic energy.

Normal fault

Thrust fault

Strike-slip fault