11.3.1

Overview of Earthquakes

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What is an Earthquake?

When plates move past each other, waves (vibrations) are created. There are different aspects of an earthquake:

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Epicentre

  • The epicentre is the point directly above the centre of the earthquake on the earth’s surface.
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Focus

  • The focus is where the pressure is released underground and where the energy radiates out from.
  • This is the place with the strongest waves that cause the most damage.
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Shock (seismic) waves

  • Energy is released from the focus in shock waves (called seismic waves).
  • The most damage will occur at the places where the shock waves are strongest (closest to the epicentre).

Earthquakes

An earthquake is a sudden or violent movement within the Earth’s lithosphere that is followed by a series of shocks. An earthquake happens when the Earth’s tectonic plates move and cause the ground to shake.

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Earthquakes can happen at all plate margins

  • At divergent margins, pressure can build up from cracks in the plates when they move apart. This can cause earthquakes.
  • At convergent margins, a plate can get stuck as it moves under another. This can cause earthquakes.
  • At conservative margins, there can be friction between plates because they aren't smooth. This can cause earthquakes.
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Plates forcing their way past each other

  • As plates move past each other, pressure builds up from the friction between them.
  • When the pressure is sufficient, the plates give way. The tectonic plates will surge past each other and the ground will shake from this violent movement.

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1Geography Skills

2Geology of the UK

3Geography of the World

4Development

5Weather & Climate

6The World of Work

7Natural Resources

8Rivers

9Coasts

10Glaciers

11Tectonics

12Climate Change

13Global Population & Inequality

14Urbanisation

15Ecosystems

16Life in an Emerging Country

17Analysis of Africa

18Analysis of India

19Analysis of the Middle East

20Analysis of Bangladesh

21Analysis of Russia

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