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Course, Subject

Earth Science, Math, Science & Technology, Literacy in Science and Technical Subjects (NYS 6-12 Common Core)

Description

Students will calculate tsunami speed and determine the time each tsunami takes to travel to specific locations in each of the scenarios presented.

This lesson is suggested to be used after viewing the PBS/NOVA special: "Waves That Shook the World." In this program, NOVA explores what happened and why when the December 26, 2004, tsunami developed off the Sumatran coast.

The program:

• tracks the Indian Ocean tsunami as it progresses outward from its epicenter.

• notes how Earth's continental plates can create earthquakes when they collide.

• describes how the tsunami developed from an earthquake that occurred at a subduction zone off the Sumatran coast.

• relates how the Pacific Tsunami Warning Center in Hawaii first registered the earthquake but, due to lack of any tsunami sensor networks in that region, was unable to know if a tsunami had formed.

• recounts through descriptions and animations how the tsunami developed after the earthquake, how it traveled in the open ocean, and how it amplified as it neared the shoreline.

• details the influence of coastal morphology and seabed gradient on the tsunami's destruction.

• reviews the four main causes of tsunamis—earthquakes, meteor impacts, volcanic or other explosive eruptions, and above-water and undersea landslides.

• states that while, by some estimates, tsunamis pose a direct threat to about one-quarter of the world's population, protection against them remains a matter of cost and politics.

• speculates what could happen if a major earthquake occurred at the Cascadia subduction zone off the Pacific Northwest coast or if the Cumbre Vieja volcano in the Canary Islands collapsed into the sea.

Taping Rights: Can be used up to one year after the program is taped off the air.

Objectives

To calculate approximate speeds and travel times for sample tsunamis.

Materials

• copy of the "Tracking Tsunamis" student handout (one per team/group)
• copy of the "Tsunami Scenarios" student handout (one per team or group)
• copy of the "World Map" student handout (one per team/group)
• calculator with square root function (one per team/group)
• drawing compass (one per team/group)
• ruler (one per team/group)
• World Atlas
• Tracking Tsunamis student handout.pdf
• Tsunami Scenarios.pdf
• Tsunami World Map Student Handout.pdf

Procedure

1. Review subduction zones and how earthquakes occur in these zones. (See Activity Answer for more information- available at: http://www.pbs.org/wgbh/nova/teachers/activities/3208_tsunami.html#answer)
2. Draw a subduction zone on the board and review with students how the December 26, 2004, earthquake off of the Sumatran coast created a tsunami which is a caused by the massive displacement of water from its equilibrium position. Gravity worked to restore the water to its equilibrium position. The waves traveled from their place of origin in all directions and energy from the quake was transferred by the water. Tsunamis, because of their long wavelengths, lose little energy as they travel. (The rate at which a wave loses energy is inversely proportional to its wavelength.)
3. Inform students that there is a formula that can be used to estimate the speed of the wave created from this energy. The formula is used to measure the speed of ocean waves, like tsunamis, that have very long wavelengths relative to the depth of the water. Tsunamis can have wavelengths greater than 700 kilometers (the average ocean depth is 3-4 kilometers). The formula estimates the tsunami's speed while it is in deeper waters (as it approaches shallower coastal waters, the tsunami slows down, its wavelength shortens, and its height increases).
4. Brainstorm with students some factors that may play a role in the speed of a tsunami. (Student responses may include the magnitude of an earthquake, the amount of displaced water, and the depth of the water.)
5. Tell students that the formula to approximate tsunami speed considers the depth of the water and the acceleration due to gravity. The formula is: Speed = square root of the product of g (acceleration due to gravity) and d (water depth in meters) where speed (meters/second) = square root of g (acceleration due to gravity, which is 9.81 meters/second2) x d (water depth in meters)
6. Have students work with a partner. Provide each team with a copy of the handouts and other materials. Review the handouts with them. Tell students that they will use the speed formula to calculate tsunami speed and determine the time each tsunami takes to travel to specific locations in each of the scenarios presented. Students can check their distance estimates at: http://www.chemical-ecology.net/java/lat-long.htm
7. Students will need to convert their answers, which will be in meters/second, to kilometers/hour. Help students think how they might move the decimal point to accomplish the last step in this conversion.
8. To conclude, hold a class discussion about the order in which the tsunami will strike each location (1st, 2nd, or 3rd).
9. Have teams share some ways people at each location might prepare for the approaching tsunami. (Some considerations are evacuating people to high ground, alerting hospitals, deciding whether there is time for help from outside the country, or sending people away by boat.)
10. As an extension, ask students to research why and how the Pacific Tsunami Warning Center was developed and what future plans are being formulated for a worldwide tsunami warning system.

Websites/Resources

• NOVA Web Site—Wave That Shook the World: www.pbs.org/nova/tsunami/
  In this companion Website to the program, find out about how well officials can prepare for the next big tsunami, read an Ask the Expert feature, see how the Indonesian event unfolded, and delve into the global history of these seismic sea waves.
• Calculating the Threat of Tsunami: www.worldatlas.com/aatlas/imageg.htm
  Maps latitude and longitude for cities, towns, and villages.

Related Academic Standards

New York State

WST.9-10.6 Use technology, including the Internet, to produce, publish, and update individual or shared writing products, taking advantage of technology's capacity to link to other information and to display information flexibly and dynamically.

WST.11-12.6 Use technology, including the Internet, to produce, publish, and update individual or shared writing products in response to ongoing feedback, including new arguments or information.

MST2.C.ES.IS.1.1 Students access, select, collate, and analyze information obtained from a wide range of sources such as research data bases, foundations, organizations, national libraries, and electronic communication networks, including the Internet.

MST2.C.ES.IS.3.1 Students discuss how applications of information technology can address some major global problems and issues.

MST4.C.ES.PS2.1 Students use the concepts of density and heat energy to explain observations of weather patterns, seasonal changes, and the movements of the Earth’s plates.

MST4.C.ES.PS2.2 Students explain how incoming solar radiation, ocean currents, and land masses affect weather and climate.