Hands-On Center

(Earthquakes-The Rolling Earth)

Lesson #4

Earthquake Waves

Shock Waves

Materials:

1. Plastic Table
2. Three cups of sand
3. Rubber Mallet

1. The students will pour three cups of sand on the top of a plastic table near the edge.
They will tap the table lightly with the rubber mallet. When they tap the table lightly they will see the sand "jump" into the air.
The teacher should explain that as rocks snap and break at the focus of an earthquake shock waves are sent out in all directions. The "jumping sand" represents the release of the energy from the hammer through the plastic table.
2. The students should move the sand farther away from the point of contact and see what happens.
The farther away the sand is from the source of energy (tapping of rubber mallet) the less the sand jumps. This represents the fact that the farther you are from
the epicenter the less you will feel the earthquakes shock waves.
3. The students should move the sand to the opposite side of the table and tap lightly. They should observe a very small movement of the sand.

4. Shear Waves
Materials: Jump Rope
Two students will hold the ends of the jump rope and raise their hands up and down shaking the jump rope and producing S waves. The waves in the jump rope will have an up and down motion.

The teacher will explain that the S waves of an earthquake look like the waves produced by the shaking of the jump rope. These are secondary waves and they will learn more about these in the lesson "Earthquakes-The Rolling Earth" on the computer.

Compression Waves
Materials: