Page 429 - Laboratory Manual in Physical Geology

A CTIVIT Y 16.1 Earthquake Hazards Inquiry

Name: ______________________________________ Course/Section: ______________________ Date: ___________

A. Obtain a small plastic or paper cup. Fill it three-quarters full with a dry sand. Place several coins upright in the sediment
so they resemble vertical walls of buildings constructed on a substrate of uncompacted sediment. This is Model 1. Observe
what happens to Model 1 when you simulate an earthquake by tapping the cup on a table top while you also rotate it
counterclockwise.

1. What happened to the vertically positioned coins in the uncompacted sediment of Model 1 when you simulated an
earthquake?

2. Now make Model 2. Remove the coins from Model 1, and add a small bit of water to the sediment in the cup so that it is

moist (but not soupy). Press down on the sediment in the cup so that it is well compacted, and then place the coins into
this compacted sediment just as you placed them in Model 1 earlier. Simulate an earthquake as you did for Model 1. What
happened to the vertically positioned coins in the compacted sediment of Model 2 when you simulated an earthquake?

3. Based on your experimental Models 1 and 2 above, which kind of Earth material is more hazardous to build on in
earthquake-prone regions: compacted sediment or uncompacted sediment? (Justify your answer by citing evidence from
your experimental models.)

4. Consider the moist, compacted sediment in Model 2. Do you think this material would become more hazardous to build
on, or less hazardous to build on, if it became totally saturated with water during a rainy season? To find out, design and
conduct another experimental model of your own. Call it Model 3, describe what you did, and tell what you learned.

5. REFLECT & DISCUSS Write a statement that summarizes how water in a sandy substrate beneath a home can be
beneficial or hazardous. Justify your reasoning with reference to your experimental models.

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