2. By: Kjerstin Olsen

4.  Earthquakes are usually caused when rock underground suddenly breaks along a fault.

5.  This sudden release of energy causes the ground to shake.

6.  When two blocks of rock or two plates are rubbing against each other they stick. The rocks do not slide smoothly, they catch on each other. After a while, the rocks break because of all the pressure built up. When the rocks break, an earthquake occurs.

7.  The spot underground is called the focus of the earthquake.

9.  The plate directly above the focus, the area on the surface, is called the epicenter of an earthquake.

13. Credits: www.geo.mtu.edu/Upeis/why.html