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Most earthquakes occur at fault lines where two crustal plates collide or move past each other. As rock is stretched and squeezed, pressure builds up. When the stress becomes too great, plates suddenly jerk and shift. Because of these movements, earthquakes can collapse buildings and tear roads apart.

Topics and Connections:

• Earthquakes
• Motion of Earth's plates

Materials:

• marker

Directions:

Students:

• Hold your hands together, palms down, so your index fingers are touching.
• Have someone else draw a line across both hands, just below the bottom knuckles. This represents a road that goes across a fault line, where the Earth may shift.
• Suddenly raise or lower one hand a small amount, or suddenly shift one hand an inch forward or back-ward, or move them slightly apart.
• What happens to the 'road' in each case?

Questions To Ask:

• Why might this happen to the ground?
• What would happen if you were on the road? How would this affect people living near the road?
• What if there were a river, a railroad, or a bridge at this spot?

Follow Up:
Work in groups to design a more detailed community

• Get two empty shoeboxes per group (empty shoeboxes may be obtained in quantity from shoe stores). Remove the lids, and place the boxes upside down next to each other, so their bottom sides are touching. If shoeboxes are not available, use pieces of cardboard.
• Using markers, paint, crayons, etc., have students draw a road that runs across the two boxes, and then fill in the surrounding 'countryside'. Discuss what types of buildings, land features, etc. should be included.
• Once the models are finished, demonstrate various types of earth motion that can happen in an earthquake.

Teachers:

• Introduce the specific vocabulary geologists use. When a block of ground (one shoebox) shifts down it is called a normal fault. When a block (shoebox) shifts up it's a reverse fault. When one slides along another it's called a lateral (or strike-slip) fault. When blocks move apart it creates a fissure.

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