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Earthquakes make the earth shake. If the earthquake is large or structures aren't reinforced, buildings can collapse. Collapsing buildings and falling objects cause most earthquake injuries. Researchers are working on new ways to reinforce buildings and keep people safe.

Topics and Connections:

• Earthquakes
• Architecture and engineering

Materials:

• 2 thick hardback books or boxes, equal in size
• shoebox lid or lunch tray
• box of sugar cubes or other small cubes

Directions:

Teacher:

• Discuss what seems to have made buildings more or less likely to topple during the 'earthquake'.

Students:

• Mark a spot in the center of the lid or tray, and draw a circle radius 3 or 4 inches around it. The spot will mark the epicenter where an earthquake will occur.
• Rest the lid or tray on top of two books (or boxes), so the ends of the tray are supported, but the center isn't.
• Build structures somewhere on the circle using sugar cubes. Each structure should use between 5 and 15 sugar cubes, and may be as high or wide as space allows.
• Draw each structure.
• When all the 'buildings' are in place, tap the lid lightly from directly below the center of the circle. A small hole made in the lid through the spot will make it easier to find the exact place to tap.
• Increase the strength of your tapping until one of the structures falls over. Record which one it was, then continue tapping more strongly until only one remains standing. Keep track of the order in which they fell. Gather up the sugar cubes from the fallen 'buildings', but leave the remaining one in place.
• Try to design new sugar cube structures that will outlast the survivor of the last quake.
• Repeat the quake and record your results.

Questions to Ask:

• What damage can an earthquake do to a building even if it doesn't collapse. Do you see this happening in your surviving 'buildings'?
• What reasons are there for not building structures that are safer in earthquakes?

Follow Up:

• Experiment with different types of earthquakes: shaking the lid instead of tapping it, tapping very slowly and steadily or very quickly, tapping the side of the lid rather than the bottom...
• Place buildings at different distances from the epicenter of the quake.
• Find "better" materials to build structures from and try again.

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