Earthquakes - cause and measurement

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  • Created by: Jess
  • Created on: 27-05-13 14:35

Earthquakes occur at all three types of plate margin

1) Earthquakes are caused by tension that builds up at all three types of plate margin:

Destructive margins- tension builds up when one plate gets **** as it's moving down past the other into the mantle.

Constructive margins- tension builds along cracks within the plates as they move away from each other.

Conservative margins- tension builds up when plates that are grinding past each other get stuck.

2) The plates eventually jerk past each other, sending out shock waves (vibrations). These vibrations are the earthquake.

3) The shock waves spread out from the focus- the point in the Earth where the earthquake starts. Near the focus the waves are stronger and cause more damage.

4) The epicentre is the point on the Earth's surface straight above the focus.

5) Weak earthquakes happen quite often, but strong earthquakes are rare.

Earthquakes can be measured using two different scales:

1) The Richter scale:

This measures the amount of energy…


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