What are earthquakes and how are

they formed?Video here

What are earthquakes and how are they formed?

What are earthquakes and where do they occur?

They can occur at all 4 major plate boundaries but the most severe earthquakes are normally found at CONSERVATIVE and DESTRUCTIVEboundaries.

CONSERVATIVE

DESTRUCTIVE

Your Turn! _____________ are caused when two

_________ moving past each other become ‘stuck’ for a while, so ______ builds up. Eventually the stress becomes so great that the ______ breaks and moves suddenly. The point where the ______ actually breaks is called the _______ , which is __________________. The point on the surface directly above the focus is called the ________ . When plates move suddenly ________ waves are sent out which can cause a lot of _________.

epicentre tension focus shock plates underground crust

damage Earthquakes rock

How can we measure earthquakes?

Earthquakes are measured using the Richter Scale. This measures the magnitude of a tremor (how powerful it is) using an instrument called a seismograph.

Although the Richter Scale has no upper limit, the largest known shocks have had magnitudes in the 8.8 to 8.9 range. It is a logarithmic scale which means that a size ‘6’ on the Richter Scale is 10 times larger than a size ’5’ and 100 times larger than a size ‘4’.

What are earthquakes and how are they formed?

What are earthquakes and how are they formed?

A seismograph

What are earthquakes and how are they formed?

TASK

• In pairs complete a story board for a BBC documentary showing how earthquakes occur.

• Sketch out what would be in 8 of the different scenes from your programme, include a written description of what is happening.

What are earthquakes and how are they formed?

http://www.bbc.co.uk/bitesize/ks3/geography/physical_processes/plate_tectonics/activity/