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 earthquakes 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.
The amount of damage caused by an earthquake depends on many things. A major earthquake can cause very little damage if it occurs far away from towns and cities. In Haiti there were many buildings in a small space. Many of the buildings were old or very badly built. They collapsed during the earthquake and 1.5 million people were left without homes. It is a frightening reminder of how much damage earthquakes can cause.