1. What are earthquakes
and how are
they formed?
Video here
What are earthquakes and how are they formed?

2. 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
DESTRUCTIVE
boundaries.
CONSERVATIVE
DESTRUCTIVE

3. 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

4. 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?

5. What are earthquakes and how are they formed?

6. A seismograph
What are earthquakes and how are they formed?

7. 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/