Every country in the world sits on top of a large sheet of rock. Earthquakes are caused by the movement of these sheets of rock and are measured on the Richter Scale. Most earthquakes are just tremors which measure 3 or less on the Richter Scale. But each year there are about eighteen earthquakes which measure between 7 and 7.9. These are major earthquakes. The earthquake that destroyed Kobe measured 7.2 on the Richter Scale. The earthquake in Haiti measured 7 on the Richter Scale. Geologists knew that two sheets of rock met and formed a sixty-five kilometer fault line near Port-au-Prince. After the earthquake,they discovered that the two sheets of rock had moved nearly 2 metres in opposite directions against each other.