Lesson 2: Earthquakes and Volcanoes

Explain to your child that earthquakes are shaking, rolling, or sudden movements of the earth's surface. In the U.S., the west coast is the most likely place for earthquakes to occur. Ask your child to locate the west coast on a map of the U.S. Earthquakes usually last less than one minute but can cause substantial damage to homes and buildings.

Cut two pieces of cardboard 14 inches by 14 inches and place one on top of the other. Ask your child to gather small action figures or dolls and to set them up on the cardboard. She can also include small cars and houses. Now lightly move the two pieces of cardboard together for ten seconds. Ask your child to describe what happened. Set up anything that fell over and rub the cardboard together more quickly for about 30 seconds. Ask your child to describe what happened.

Explain that the earth's crust or surface is divided into plates. When these plates collide and pull apart, energy is produced that is changed into wave movements. These waves shake the surface of the earth. These waves are similar to sound waves in the way they move out from the source. When the earth's surface shakes, it can damage buildings and other objects that are built or sitting on top of the earth's crust. Bridges can collapse, and mountains can rise. Earthquakes even create large cracks on the earth's surface.

Help your child locate information about earthquakes on the Internet. The following website provides useful resources for learning more about earthquakes:

Explain that a volcano is a landform where volcanic material has accumulated above the surface of the earth, forming a cone shape similar to a small mountain. Describe that at the top of the cone is a bowl-shaped vent called a crater. When a volcano is active, lava (hot liquid rock) is ejected through the vent from inside the earth. Volcanoes and earthquakes both cause movement in the crust of the earth. The experiment on the page, "Volcanoes," will demonstrate how heat is produced as the crust of the earth moves. Review the idea that heat causes change in the environment.

After the demonstration, ask your child what happened. Ask her why the cardboard was partially lifted. Ask her how her hands felt after she rubbed them together (hot). Then ask her how the refrigerated bottle felt (cold). Explain that the heat from her hands changed the temperature of the air in the bottle. When air gets warm, it expands, pushing the gas (air) up with enough force to partially lift the paper.

In a volcano a very similar effect occurs. Sections of the earth's crust (plates) rub against one another and produce heat. This heat causes the rocks to vibrate. When the rocks vibrate very quickly, they break away from each other and become liquid rock (magma). The materials inside the Earth warm and expand, forcing heat and rock through the Earth's surface. When magma exits the vent of the volcano, it is called lava. Ask your child how heat causes the crust of the earth to move.

For this activity, your child will create a model of a volcano to help her understand more about how changes in the Earth cause volcanoes to erupt. Follow the instructions on the "Erupting Volcano" page.

After the experiment, ask your child why the contents of the bottle were pushed out. Explain that baking soda (a solid) and vinegar (a liquid) react with each other and form a gas called carbon dioxide. The gas expands in the bottle and pushes the liquid and flour out of the bottle. The mixture of gas, flour, and liquid form foam. This foam simulates the magma/lava in a volcanic eruption. Ask your child why volcanoes erupt.

Review that a volcano can change the environment of the land. If a volcano erupts, the lava will flow over the land that surrounds the volcano. This hot lava will burn the trees, grass, and other plants around the volcano. When the lava cools, it becomes large black volcanic rock that covers the surface of the land. On the Internet look at pictures of the environment around active volcanoes and around volcanoes that have been dormant for many years. Discuss the difference in the land.