Plate Tectonic - Hazards (2)  Lab
 OBJECTIVES: Simulating strong, moderate, and weak earthquakes. Assessing what a mayor should do during a strong, moderate, and weak earthquake.  VOCABULARY: aftershock moderate strong weak MATERIALS: Primary Shaker Table or shaker boards toys Students decide what actions a town mayor should take after an earthquake. Ground rupture, Pt. Reyes, California, 1906
BACKGROUND:

This lab is designed to stimulate discussion of what to do during an earthquake. Letting the students play the part of a mayor will help them realize that they may have to assume responsibility in case of a major disaster. The important points of the lab are that during a weak to moderate earthquake, the mayor should check with the local agencies and the hospitals. However, during a strong earthquake almost all aspects of the city have to be looked at to see if they survived the event intact. Areas such as shopping centers, hospitals, roads, and homes must be examined in order to determine if their use is safe. Utilities and other services must also be evaluated.

PROCEDURE:
1. Explain and contrast the effects of moderate and severe earthquakes to the students. Have the students suggest how damage levels would differ between the two levels of shaking. You may also want to include a brief discussion concerning aftershocks. Aftershocks may happen after a big earthquake. Many times you have to be careful of these smaller earthquakes, especially the ones that occur within 48 hours of the initial earthquake.

2. If necessary, construct Primary Shaker Tables or shaker boards before the lab begins. The Primary shaker table can control the different intensities better, but the shaker board is a more correct analog because it can shake in many directions. If your class is familiar with lab procedures, we recommend the shaker boards. Directions are given below. Make enough tables for the students to work in groups of 2 or 3. Here are directions:

HOW TO CONSTRUCT A PRIMARY SHAKER TABLE

If necessary, construct Primary Shaker Tables or shaker boards before the lab begins. The Primary shaker table can control the different intensities better, but the shaker board is a more correct analog because it can shake in many directions. If your class is familiar with lab procedures, we recommend the shaker boards. Directions are given below. Make enough tables for the students to work in groups of 2 or 3. Here are directions:

Materials:

8 long stemmed brads or nails
4 strong, thick rubber bands
marbles
cardboard box with lid
string
plastic container lid

Directions:

1. Cut a section from the cardboard box lid so that it will fit inside of the cardboard box as shown in the picture below.
2. Take 4 brads and insert them from the inside of the cardboard box so that the stems fall outside of the box. Insert the remaining four brads into the cut lid of the box. Make sure that the brads are not directly on the edge as this will cause the lid to tear when it is pulled.
1. Fasten the rubber bands to the brads inside of the cardboard box. Fasten the other ends of the rubber bands to the brads on the cut lid. Leave the lid inside of the box.
2. Place several marbles in a container top. Put the marbles in their container under the cardboard lid in the box, to allow it to move freely when up or down.
3. Make a small hole in one end of the box. Attach a piece of string to one end of the lid and. insert the opposite end of the string through the hole in the box. This moves the lid. Don't forget to tie a knot at the end of the string where comes out of the box. This will prevent it from going back inside. Your "primary shaker table" is complete.

HOW TO CONSTRUCT A SHAKER BOARD

1. Cut particle board or use a heavy wood into 12 x 18 inches. The thickness should be about 3/4 inch thick.
2. Place the marbles in the plastic top. The marbles will act as ball-bearings in the experiment.
3. Balance the shaker board on top of the marbles. This completes the shaker table.

1. Demonstrate how the shaker table or shaker board works to the class. When it is "jolted", it simulates the movement of the Earth's surface (an earthquake). The earthquake creates energy that moves along the surface of the shaker table as waves. Control the "intensity" by how fast you shake the board. Demonstrate to students that a strong earthquake occurs when you shake fast; a weak earthquake occurs when you shake it less violently; a moderate earthquake occurs when you shake it somewhere in between.

2. Divide the students into groups. Instruct each group to make a little village on the shaker table. Illustrate to them how to shake the village at the different intensities. Have the students rebuild the village in exactly the same way after each demolition. After each shaking, review what happens to the village. Discuss what happens after a strong, moderate, and weak earthquake. The conclusion should be that the higher the intensity, the more the damage to the homes. A small earthquake, which most earthquakes are, causes very little damage. You may want to tell the students that earthquakes only cause damage where homes and buildings are not constructed to withstand shaking.

3. Have the students complete the worksheet. Have them decide what the mayor should be concerned about after each mock earthquake. The list includes structures that may need to be evaluated, as well as government agencies to contact. There is room on the lab sheet to include other areas of potential concern, as well as additional agencies to contact. You can look on the Internet or in the telephone book, under "GOVERNMENT" to find the appropriate agencies, which you should write in on the lab sheet.