<em><u>Earthquakes are usually caused when rock </u></em><em><u>or</u></em><em><u> </u></em><em><u>plates</u></em><em><u> </u></em><em><u>underground suddenly breaks along a fault.</u></em>
This sudden release of energy causes the seismic waves that make the ground shake.
When two blocks of rock or two plates are rubbing against each other, they stick a little and start building up pressure in the two plates. When the pressure inside the plates overcome their force of sticking and the plates break causing earthquake .