- Learn what tsunami are: how they form, what their characteristics are, and why they can cause damage so far from their sources.
- Learn about the properties of shallow-water waves vs. deep-water waves, and why tsunami are shallow-water waves.
- Use a spreadsheet to calculate whether or not a wave traveling in a basin of known depth is a shallow-water wave and, if it is, what its velocity would be.
- Calculate the velocity of tsunami waves in different parts of the ocean.
- Calculate travel times given a distance and a velocity, and apply this principle to the transport of sound waves from Krakatoa Volcano to Rodriquez Island in 1883. The relationship between travel time, velocity, and distance is the main quantitative concept in this module.
- Use a spreadsheet to calculate the travel times for a hypothetical tsunami generated near Lisbon, Portugal, across the Atlantic Ocean.
In the process the students will
- Learn that tsunami are singular waves caused by a disturbance that can travel across entire oceans at great speed.
- Discover that the velocity of a shallow-water wave depends only on the water depth.
- Discover that tsunami are shallow-water waves throughout the entire ocean, by virtue of their enormous wavelength.
- Learn about tsunami risk to the eastern US.
- Learn about the bathymetric regions of the oceans, and the different depths found in each.
- Discover how the arrival time of a tsunami depends on its path, particularly how long it spends on shallow vs. deep parts of the ocean.
Context for Use
Description and Teaching Materials
Tsunami Time (PowerPoint 5.7MB May15 12)
Optimal results are achieved with Microsoft Office 2007 or later; the module will function in earlier versions with slight cosmetic compromises. If the embedded spreadsheets are not visible, save the PowerPoint file to disk and open it from there.
The above PowerPoint presentation is the student version of the module. The embedded spreadsheet consists of a template for students on which students complete their work and answer the end-of-module questions, and then turn in for grading. Since this module is designed as a stand-alone resource, instructions for extracting and saving the embedded spreadsheet are included in the PowerPoint presentation.This module is offered in two versions: a traditional SSAC version and a new auto-feedback/graded (AFG) version. The AFG version: (a) provides automatic and immediate feedback to incorrect answers, including formulas; (b) requires students to complete tasks sequentially by not allowing them to advance until they've completed a task perfectly; and (c) automatically computes a grade and encrypts it into a code the students submit to verify successful completion. The files needed for this version can be accessed here .
Teaching Notes and Tips
This module is constructed to be a stand-alone resource. It can be used as a homework assignment, lab activity, or as the basis of an interactive classroom activity. It has been used as a mid-course module in Hazards of the Earth's Surface, an online service course at USF designed for non-majors, for the last two years. Students should be somewhat familiar with the concept of earthquakes, faults, and tsunami waves, though the needed math is introduced and explained in the module.
References and Resources
Gutscher, M-A., 2004, What caused the great Lisbon earthquake? Science 305 (5688) 1247-1248.
Gutscher, M-A., 2006, The great Lisbon earthquake and tsunami of 1755: lessons from the recent Sumatra earthquakes and possible link to Plato's Atlantis, European Review 14, 181-191.
Tsunamis in the Atlantic Ocean, from the Maine Geological Survey, available at: http://www.maine.gov/doc/nrimc/mgs/explore/hazards/tsunami/jan05.htm
Ward, S.N. and Day, S., 2001, Cumbre Vieja Volcan–potential collapse and tsunami at La Palma, Canary Islands, Geophysical Research Letters 28, 3397-3400.