When an earthquake strikes, it causes millions of dollars in damage to homes and other property, not to mention the toll in human lives. There is an entire field of research dedicated to studying ways to lessen this damage through advanced engineering. This field is appropriately called earthquake engineering. Earthquake-proof houses are one of the developments to emerge from this field. They are built in earthquake-prone areas and are designed to withstand tremendous forces. You can build a model earthquake-proof house with your child as a school project.
Turn the large cardboard box upside down and make a small mark 1-1/2 inches from the top. Draw a straight, horizontal line all around the sides of the box. Cut the box with the craft knife along this line.
Turn the cut section over. This is the base of your earthquake simulator or "shake table." Fill this box with the marbles, creating a layer that is about 1/2-inch high and still loose enough for the marbles to move slightly.
Cut a square of cardboard, 18 inches on all sides, from the remaining scraps of the large cardboard box. Punch out 12 equally-spaced holes along the sides of the cardboard square. There should be a hole in each corner and two holes on each side. The holes should have 4 inches of space between them
Punch 16 holes into the box filled with marbles. There should be four holes on each side, none near the corners of the box, each spaced 4 inches apart.
Place the cardboard on top of the marbles centring it in the middle of the box. Remove 16 medium-sized rubber bands from the bag and cut them open. Tie one end of each rubber band through one hole in the box, then tie the other end to the corresponding hole on the cardboard square. The corners of the square will have two rubber bands tied to them.
Cut out two, 1-foot cardboard squares from the remaining cardboard.
Glue the four mini-spring toys to the four corners of one of the boards, one in each corner.
Glue the other board on top of the mini-springs. Make sure it is neatly lined up with the edges and sides of the bottom board.
Have the children who will be participating in the project make a small house structure of their own design on top of the shake table without the base-isolation device. The house can be as tall or wide as they want as long as it stands and fits on the square.
Have the children shake the box gently, then with gradually increasing force. The house should rock and eventually tumble over. Let a volunteer time the experiment to see how long it takes to fall.
Place the base-isolation device from Section 2 on top of the shake table. Have the children rebuild another house on top of the base-isolation device.
Shake the shake table again in the same manner and measure how long it takes the house to fall, if it ever does. Note any differences in the time it takes for the house to fall. Ask the children to consider any changes in design that may improve strength.
The mini-spring toys are spring-shaped, miniature versions of the Slinky toy. You can find them in party supply stores or in certain toy vending machines. This project involves creating a shake table and a base-isolation model. Earthquake engineers actually use a device called a shake table to simulate earthquakes for actual earthquake-proof homes. The base-isolation method is one earthquake-proofing building technique. It allows the building's foundation to move with the earth, minimising stress on the building's structure. This project is designed so that either a large number or small number of children can participate. If the group is large, with 10 or more students, separate them into smaller units of two or three, then have each unit build its house and test it with and without the base-isolation device. Have the children who perform the experiment change their building designs. Perhaps a taller building withstand the shaking better. Also consider changes to the base-isolation device, such as whether added springs would help.
Craft knives are sharp and can be dangerous to use. Make sure students know how to use them safely, or that an adult cuts the cardboard.