Earthquake Experiment

In 1989 a powerful earthquake struck San Francisco and caused massive damage to the city. In 1995 an earthquake in Kobe Japan killed 5096 people and devastated the city.

Damage for both of the earthquakes was widespread, but was considerably greater in certain parts of the cities. This experiment is designed to demonstrate one reason why earthquake damage varied in different parts of the cities.

Because of the high demand for housing, and the limited area to build it, both cities have extended their development out over the nearby estuary areas. By trucking in dirt and filling in near-shore wetlands the cities have been able to build out over these areas. Therefore both cities have sections built over “dry” soil and bedrock, and sections built over “wet” soil and bedrock. One of the “wet” areas of San Francisco is called the Marina district.  This project is worth 20 POINTS EXTRA CREDIT TEST GRADE.

THE EXPERIMENT

In the experiment the two tubs of sand are used to represent the two different parts of each city. A tub of dry sand represents the older part of the city built on dry soil and bedrock. A tub of wet sand represents the newer sections of each city that have been built on infilled in parts of the bay. A brick is used to represent a skyscraper. A sander is used to make a simulated earthquake. In the experiment we will put the brick in each tub, turn on the earthquake and watch what happens. The objective of this experiment is to show one of the reasons that an earthquake may be more dangerous in one area than another.

Materials–

* Two small washtubs,
* enough sand to half-fill the tubs
* power sander (simulates seismic waves)
* brick
* trowel
* bungee cord (cheaply bought from Wal-Mart)
* water
* timer

Procedure:

1. Two tubs are filled with dry sand.
2. Water is added to one of the tubs.(Note: the more water in the wet sand the better– water should form small pools at the surface.)
3. A simulated building (brick) is balanced on the sand in the tub.
4. The simulated skyscraper (the brick) is placed on the sand in the dry sand tub, a simulated earthquake (a sander attached to the tub with a bungee cord) is applied and timed.
5. This is repeated at least 4 times (to provide an average time).
6. The procedure is then repeated using the tub with wet sand (Note: the more water in the wet sand the better– water should form small pools at the surface.
7. Use the trowel between each repetition of the wet sand experiment to stir the water into the sand).
8. Results are observed and timed.

Lab Report:

Your lab report needs to included the following sections. You need to copy and paste into Microsoft Word or you can write neatly on a sheet of paper/computer paper

Question: How does the type of foundation a building is built on affect how long the building can withstand an earthquake

Hypothesis: What is your hypothesis about what will happen in this experiment?

Data/Results

TUB 1- The Dry sand (The part of San Francisco built on dry soil )

Times:

1.

2.

3.

4.

Total time:_____________Average time:__________

TUB 2 – The wet sand (The part of San Francisco built on filled-in Bay)

Times:

1.

2.

3.

4.

Total time:_____________ Average time:__________

Results (Pictures must be included in your experiment.) This is where you discuss your observation and put your data into sentence form

For 5 points extra credit add a bar graph comparing the average times

Conclusions:

1. Was your hypothesis correct? Explain your results (use your observation and data in your answer)
2. If you had a choice where would you build your house? Why?
3. What are some other hypotheses you can test?