1. Earthquakes[Date] Today I will: - Know what an earthquake is. - Know how the strength of an earthquake is measured. Geography Earth Forces

2. Geography Earth Forces Earthquakes are the shaking of the Earth’s surface. They are caused by the sudden movement of tectonic plates. Most earthquakes only last a matter of seconds!

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6. Geography Earth Forces Earthquakes occur when rocks inside the crust move suddenly. This sudden movement causes shock waves to travel out in all directions. There are 3 types of shock waves: - P Waves (Push/Primary) make the rocks move up and down – the fastest waves. - S Waves (Shake/Secondary) make rocks move from side to side. - L Waves (Long) spread out along the surface – slowest but most destructive.

7. Geography Earth Forces The intensity of earthquakes are measured with a ‘Seismometer’.

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9. Geography Earth Forces And these results are shown on a seismograph

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13. Geography Earth Forces Earthquakes can cause a lot of destruction and even start fires. Geography Earth Forces

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