CLASSROOM ACTIVITY

LENGTH:

Two class periods

GRADE LEVEL:

6-8

SUBJECT AREA:

Earth Science

OBJECTIVES:

Students will understand the following:

1. Tsunamis, huge tidal waves, in both oceans and fjords (narrow inlets of the sea with steep cliffs on either side) can create massive destruction.

2. Ocean tsunamis and fjord tsunamis behave differently, due to the difference in width.

3. Ocean tsunamis are caused by undersea earthquakes, volcanic eruptions, or landslides; or by the impact of a large meteorite falling into the ocean. Fjord tsunamis are caused by broken portions of icebergs plummeting into the waters.

MATERIALS:

The following materials should be distributed to each group:

Two plastic containers of the same length but different widths. (One should be significantly narrower than the other.)

Water

Masking tape

Small rock, ball of clay, or other object that can be dropped into the water-filled containers

Ruler or tape measure

PROCEDURE:

1. Review with your students what they already know about tsunamis, or tidal waves. In discussion, bring out the possible causes of an ocean tsunami: undersea earthquakes, volcanic eruptions, or landslides; the impact of a large meteorite falling into the ocean.

2. Continue the discussion by letting students know that a tsunami can also occur in a fjord—a narrow inlet of the ocean with cliffs on either side. Fjord tsunamis are generally caused by portions of icebergs plummeting into the waters.

3. Tell students that they are going to perform an experiment to find out the difference in wave patterns between tsunamis that occur in the ocean and in a fjord.

4. Divide the class into groups. The groups' first challenge is to design an experiment that will simulate the two types of tsunamis so that the differences in their wave patterns can be observed. Students should come up with a procedure similar to the one that follows.

5. Distribute materials to each group, and have them set up their experiments as follows:

- Fix a strip of masking tape down the inside of each plastic container.

- Fill each container with water so that the depth is the same in each one.

- Trim the strip of tape in each container so that it reaches half a centimeter above the water level.

6. Instruct students to drop an object from the same height into each container and measure the distance the resulting wave travels from the point of impact to where it drops below the level of the masking tape. Have students record their results.

7. With the whole class, graph the results of the experiment.

8. Hold a class discussion about the experiment. Students should be aware that the wider container represented the ocean and the narrow container, a fjord; the object dropped represented a meteorite falling into the ocean or a huge chunk of ice falling into a fjord. In discussion, ask students how they know that the difference in wave pattern was not due to difference in water depth. (The experiment required the depth of the water in each container to be the same.)

9. Continue the discussion by having students determine which type of tidal wave would cause the most destruction—one occurring in the ocean or in a fjord.

10. Have each student draw a diagram that shows the experimental design and the results of the experiment. Each diagram should be accompanied by a brief paragraph explaining in words what the diagram shows visually.

11. Have the class recommend safety precautions for both fjord regions and ocean coastal regions based on their findings.

ADAPTATIONS:

Adaptations for Older Students:

Have students use the Internet to research architectural designs for coastal buildings constructed to withstand tidal waves. Students might make models of such buildings.

DISCUSSION QUESTIONS:

1. Hypothesize why more tsunamis occur in the Pacific Ocean than in the Atlantic.

2. Compare the tsunamis that occur in a fjord as a result of an iceberg breaking apart and the tsunamis that occurs in the ocean as a result of an underwater earthquake.

3. Analyze the tsunami's wave as it approaches land and becomes a surge. Explain how undersea structures and coastline configuration affect the intensity of the wave.

4. Describe some of the ways tsunamis affect people who do not live on a coastline.

5. Describe architectural changes that would be required in order to tsunami-proof a beachfront home.

6. Explain how a tsunami alert warning system might function. Compare and contrast such a system to hurricane warning systems.

EVALUATION:

You can evaluate your students on their diagrams and paragraphs using the following three-point rubric:

Three points:diagram carefully executed; diagram clearly shows experimental design and results; paragraph clear, accurate, and error-free

Two points:diagram lacking in clarity; paragraph satisfactory, but with some errors

One point:diagram unclear; paragraph vague with numerous errors

You can ask your students to contribute to the assessment rubric by determining what labels should be included in the diagram and what information should be included in the paragraph.

EXTENSION:

Evacuation Time

Have students use a map of the Pacific Ocean floor to locate the Santa Catalina fault line. Instruct them to prepare a hazard map that shows which areas are most in danger if an earthquake or volcanic eruption should occur at the fault. Students should indicate on their maps how long they think it will take for the resulting tsunami to reach land if they use the standard of 500 miles per hour for speed of the tsunami. How would students warn the population about the approaching tsunami?

Splash-Height Analysis

Have students determine the relationship between the size of an object causing an impact in the ocean and the height of the wave it makes. Students can drop clay balls of different sizes from the same height into a plastic container of water. By lining the sides of the container with construction paper, students can measure at what height the water splashes the paper. Have them graph their results and relate their data to the effects of the 110-mile-wide crater off the coast of the Yucatan peninsula.

SUGGESTED READINGS:

“Making Waves”

Science,August 21, 1998.

This article announces a computer simulation prepared by the U.S. Geological Survey and describes the action as a tsunami strikes the coast of Papua New Guinea. The actual event killed over 2,100 people.

“Tsunamis”

Science Activities,Winter 1997.

This article discusses educational resources available from the National Geophysical Data Center. Resources include publications, slide sets, and even databases.

WEB LINKS:

West Coast & Alaska Tsunami Warning Center

Earthquake and recent tsunami information.

http://www.alaska.net/~atwc

US Dept. of Commerce Tsunami Project

Reviews tsunami hazards.

http://pmel.noaa.gov/tsunami/index.html

Welcome to Tsunami!

Describes tsunami warning system and how tsunami waves are made.

http://www.geophys.washington.edu/tsunami/welcome.html

Tsunami Data at NGDC

Provides data on tsunami waves and slides of waves.

http://www.ngdc.noaa.gov/seg/hazard/tsu.html

VOCABULARY:

crest

The top of a wave.

Context:

The crest of each wave may rise only a foot or two above normal.

fjord

A narrow inlet of the sea between cliffs or steep slopes.

Context:

The falling ice sends out a wave which spreads rapidly across the fjord. The water is deep, so, like a tidal wave, the wave is long and low, barely visible.

surge

A large wave or billow.

Context:

It builds and then breaks into a huge surge of water that rushes ashore.

trough

The lowest point between waves.

Context:

For every wave peak there is a trough. If the trough comes first, then the sea is sucked out before the wave comes in. It is a classic danger sign.

tsunami

A great sea wave produced by a submarine earth movement or volcanic eruption.

Context:

Near Pearl Harbor is the Pacific Tsunami Warning Center. Tsunamiis the word most scientists use for a big tidal wave.

ACADEMIC STANDARDS:

Grade Level:

6-8

Subject Area:

Earth science

Standard:

Understands basic Earth processes.

Benchmarks:

Benchmark 1: Knows how land forms are created through a combination of constructive and destructive forces (e.g., constructive forces such as crustal deformation, volcanic eruptions, and deposition of sediment; destructive forces such as weathering and erosion).

Benchmark 2:Knows how successive layers of sedimentary rock and the fossils contained within them can be used to confirm the age, history, and changing life forms of the Earth, and how this evidence is affected by the folding, breaking, and uplifting of layers.

Grade Level:

6-8

Subject Area:

physical science

Standard:

Understands motion and the principles that explain it.

Benchmarks:

Knows that vibrations (e.g., sounds, earthquakes) move at different speeds in different materials, have different wavelengths, and set up wavelike disturbances that spread away from the source.

Grade Level:

6-8

Subject Area:

geography

Standard:

Knows the physical processes that shape patterns on Earth's surface.

Benchmarks:

Benchmark 1:Knows the major processes that shape patterns in the physical environment (e.g., the erosional agents such as water and ice, earthquake zones and volcanic activity, the ocean circulation system).

Benchmark 2:Knows the consequences of a specific physical process operating on the Earth's surface (e.g., effects of an extreme weather phenomenon such as a hurricane on a coastal ecosystem, effects of heavy rainfall on hill slopes, effects of the continued movement of Earth's tectonic plates).

Benchmark 3:Understands how physical processes help to shape features and patterns on Earth's surface (e.g., the effects of climate and weather on vegetation, erosion and deposition on landforms, mud slides on hills).

Grade Level:

9-12

Subject Area:

Earth science

Standard:

Understands basic features of the Earth.

Benchmarks:

Knows how winds and ocean currents are produced on the Earth's surface (e.g., effects of unequal heating of the Earth's land masses, oceans, and air by the sun; effects of gravitational forces acting on layers of different temperatures and densities in the oceans and air; effects of the rotation of the Earth).

DiscoverySchool.com

http://www.discoveryschool.com

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