As students learn to read maps, it is important that they learn how to compare maps that show different types of information. This lesson asks them to compare maps of plate tectonics with population density maps and to analyze what these maps imply about the relationship between population and seismic hazards.

Geography, physical science

Standard 3: "How to analyze the spatial organization of people, places, and environments on Earth's surface"
Standard 7: "The physical processes that shape the patterns of Earth's surface"
Standard 12: "The processes, patterns, and functions of human settlement"
Standard 15: "How physical systems affect human systems"

Three hours

• Computer with Internet access
• Population density map (available online)
• Writing and drawing materials
• Blank Xpeditions outline maps of the United States, one for each student

Students will

• read about and discuss the theory of plate tectonics;
• map the regions of the United States that are most susceptible to earthquakes and those that have volcanoes;
• list the states that lie on plate boundaries;
• look at a population density map and explain if people avoid living in areas at high risk for earthquakes and volcanoes; and
• research specific volcanoes or earthquake zones and write pretend letters to residents of these areas describing the risks.

Ask students if they know where in the United States a volcanic eruption might occur. What about an earthquake? Have any of your students ever witnessed either of these events?

Have students learn about plate tectonics by going to one or more of the following Web sites. Ask them to take notes on the theory of plate tectonics and why volcanoes and earthquakes occur. Discuss these concepts with the class.

National Geographic: Forces of Nature—Earthquakes
National Geographic: Forces of Nature—Volcanoes
All About Plate Tectonics
BrainPOP: Plate Tectonics [Note: If you do not have a membership to BrainPop, you can only watch the movies twice in the same day.]
PBS: Intro to Plate Tectonic Theory

Give each student a blank United States outline map, and have them look at a map of Earth's major plates. Ask them to determine which areas of the United States are probably most susceptible to volcanic eruptions and earthquakes, based on what they have learned. Have them use dark colored pencils to draw the plate boundaries and light colored pencils to shade in the predicted areas of high earthquake and volcano risk on their maps.

Students can then use these U.S. Geological Survey maps of earthquake and volcano zones to check their own maps:

USGS: Volcanic Hazards
USGS: Ground-shaking Hazards from Earthquakes in the Contiguous United States

Ask students to refer to a United States political map, either in the classroom, in an atlas, or at MapMachine, and list the states that lie on plate boundaries. Have students explain what particular hazards residents of these states have to be concerned with as a result of the location where they live.

Have students look at this population density map of North America, created from National Geographic's MapMachine. They can zoom in and out on specific areas and customize the map in different ways. They can also look at a MapMachine map that shows historic earthquakes in North America.

Ask students whether there is a relationship between population density and areas of increased risk for volcanoes and earthquakes. They should address these questions, either in writing or in a class discussion:

• Have people avoided populating areas that are at risk for earthquakes or volcanic eruptions?
• Why do you think this is the case? Why do you think anyone would want to live in a region that is at risk for earthquakes and volcanic eruptions?

Ask students to choose a particular volcano (e.g., Mount St. Helens or Mount Rainier) or earthquake risk zone (e.g., San Francisco Bay or Los Angeles) and find out more about the risks associated with living near this natural hazard. They can find information at these Web sites and other Internet and print resources:

National Geographic: Forces of Nature—Earthquakes
National Geographic: Forces of Nature—Volcanoes
Life Along the Faultline
Volcano World

Have students write pretend letters to the people who live near the volcano or in the earthquake zone they chose above. Their letters should describe how the natural hazard develops and how people can prepare for the hazard.

Have students write paragraphs explaining the reasons why earthquakes and volcanoes tend to occur on plate boundaries.

Have students create population density maps of the continents with MapMachine and compare them with the Earth's major plates map or with the earthquake maps they can also make using MapMachine. Have them write paragraphs answering these questions:

• Do people tend to avoid living in places that are at risk for earthquakes and volcanoes?
• Which countries appear to face the highest risk of major damage from an earthquake or volcano? Why?

They can use an atlas or MapMachine to find out the names of countries.

All About Plate Tectonics
BrainPOP: Plate Tectonics
Life Along the Faultline
National Geographic: Forces of Nature
National Geographic: World—Red Hot Volcano Quiz
Volcano World