Topic outline

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  General

  

  • Unit forum
  • Time: 8 hours
    Level: Introductory

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  Topic 1

  Introduction

  • Introduction Page
  • Earthquakes shake the ground surface, can cause buildings to collapse, disrupt transport and services, and can cause fires. They can trigger landslides and tsunami – in short, earthquakes can be very destructive....
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  Topic 2

  1 Earthquakes

  • 1.1 What happens during an earthquake? Page
  • The Earth is an active planet, with activity occurring in the oceans, in the atmosphere and in the solid Earth itself. This unit looks at a dramatic example of solid Earth activity: earthquakes.
  • 1.2 Earthquake-triggered landslides and tsunami Page
  • As well as being highly destructive in their own right, earthquakes can also trigger two other very destructive natural hazards. One of these is a landslide. This is a rapid movement of earth materials...
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  Topic 3

  2 Why do earthquakes occur?

  • 2 Why do earthquakes occur? Page
  • What causes the apparently solid and rigid Earth to move and so produce an earthquake? Earthquakes mainly occur when the different blocks or plates that make up the Earth's surface move relative to each...
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  Topic 4

  3 Where do earthquakes occur?

  • 3 Where do earthquakes occur? Page
  • How deep in the Earth do earthquakes occur? Most earthquake foci are within a few tens of kilometres of the surface. Earthquakes less than 70 km deep are classified as shallow-focus. Earthquakes with foci...
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  Topic 5

  4 The size of earthquakes

  • 4.1 Earthquake intensity Page
  • Why are some earthquakes more destructive than others? There are three main reasons: location (an earthquake with a focus under an ocean at a large distance from land, for example, is not usually destructive,...
  • 4.2 Earthquake magnitude Page
  • The magnitude of an earthquake is a measure of the amount of seismic energy released by it, so it is a quantitative scale. The scale of earthquake magnitude is called the Richter scale. Its development...
  • 4.3 Seismic energy Page
  • It is also possible to relate magnitude to the seismic energy released by an earthquake. An increase of one unit on the Richter scale represents an increase of about 40 times in the amount of seismic energy...
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  Topic 6

  5 Summary

  • 5 Summary Page
  • Earthquakes shake the ground surface, can cause buildings to collapse, disrupt transport and services, and can cause fires. They can trigger landslides and tsunami.
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  Topic 7

  References and Acknowledgements

  • Acknowledgements Page