# Science Lab: Modeling the Richter Scale

By Marlene Gundlach

The Richter scale is used to measure the strength or magnitude of an earthquake. In this science lab, the students will model the Richter scale and analyze their findings.

## Prelab Discussion

Have the students read the entire activity and then discuss with them the following:

1. Review the Richter Scale. You may refer to my article "Comparing Earthquake Scales".
2. Have students predict which block will be easiest to knock down.
3. Discuss the different types of seismic waves and determine which type will be simulated in the model.

## Materials and Preparation

Each student or group of students will need the following:

• three blocks of wood, the following sizes: 3 x 3 x 3 cm, 3 x 3 x 15 cm, 3 x 3 x 25 cm
• a piece of cardboard large enough to hold the blocks
• masking tape
• pencil
• copy of the data table

Place the cardboard on a desk or table. Be sure the desk is level. With the tape, label the longest block 1, the medium-sized block 5, and the smallest block 9. Place the three blocks on the cardboard with the long side facing up.

## Procedure

1. Move the cardboard to create a gentle shaking for 5 seconds. Record any observations about the blocks in the data table.
2. Repeat the gentle shaking for about 65 seconds. Record your observations.
3. Repeat steps 1 and 2 and carefully use moderate and violen force to shake the blocks. Again, record your observations in the appropriate secions.

## Analysis

1. Identify the variables in this activity. (size of block, force of shaking, pattern in cardboard movement, length of shaking)
2. Which block was the hardest to knock down? (the tallest) The easiest? (the shortest)
3. Which had a greater impact on the blocks, the length of the shaking or the strength of the shaking? Why? (Answers may vary, but may include: the strength of shaking had a greater ipact because of the initial damage)
4. The label on each of the blocks corresponds to a reading on the Richter scale. The energy it takes to knock down each block relates to an earthquake of that size on the Richter scale. Which block was te hardest to knock down? What is the Richter scale number for an earthquake of that size? (The small block was the hardest to knock down. Nine is the Richter scale number for an earthquake of that size.)

## Conclusion

Ask students to complete the following activity:

• How does your model compare to the Richter scale? Write a short paragraph comparing the earthquake energy that relates to the different numbers on the Richter scale.

For a challenge, ask students to calculate the size of the blocks needed to represent earthquake energies for the rest of the Richter scale. Make enough blocks to complete an entire Richter scale set. Test the set that you make and record your observations.