earthquakes

• Earthquakes are the sudden violent shaking of the ground. This happens because the Earth's plates are constantly moving. Sometimes, because of friction, plates try to move and become stuck. Pressure builds up because the plates are still trying to move. When the pressure is released, it sends out huge amounts of energy causing the Earth's surface to shake violently.
• The point inside the Earth's crust where the earthquake originates from is known as the focus. The earthquake's energy is released in seismic waves and they spread out from the focus. The seismic waves are most powerful at the epicentre. The epicentre is the point on the Earth's surface directly above the focus.
• The Richter scale measures the magnitude of an earthquake (how powerful it is). It is measured using a machine called a seismometer which produces a seismograph. A Richter scale is normally numbered 1-10, though there is no upper limit.
• Effects of an earthquake

  • Size of the earthquake on the Richter scale - the higher it is on the scale, the more destruction it can cause
  • Level of development - whether it occurs in a rich or a poor country. Richer countries will be more likely to be able to predict, protect and prepare themselves from the effects of an earthquake
  • Depth of the focus - if it's shallow, it can be more destructive
  • Distance from epicentre - the effects of an earthquake are more severe at its centre
  • Population density - the more people living in an area, the more likely that more deaths and casualties may arise
  • Time of day - whether people are in their homes, work or travelling
• short term responce


   a response in the days and weeks immediately after a disaster has happened. Short-term responses mainly involve search and rescue and helping the injured.
• long term response


   responses that go on for months and years after a disaster. It involves rebuilding destroyed houses, schools, hospitals, etc. It also involves kick-starting the local economy.