This activity is used in an introductory oceanography course for non-majors. The class meets once a week and does not have a lab component, so this activity is used to break-up the 3 hour lecture period.

The preceding lecture should cover the difference between shallow-water and deep-water waves, provide a brief description of tsunamis, and discuss how these waves are formed and travel across the ocean. Students need to understand that the tsunami wave front propagates out in a roughly circular patter from the source location. Additionally, a general overview of how tsunami are recorded by the DART stations is useful. Students must also be familiar with contour plots and will need some direction on how to plot contours from discrete points.

This is a stand-alone exercise that is situated in the middle of a short lecture on tsunami, which is part of a longer lecture on ocean waves and currents.

Practice plotting information on a map and doing simple wave speed calculations.

Practice reading and interpreting information contained on a map. Synthesizing the information from lecture regarding the difference between shallow-water and deep-water waves to better understand how this relates to the speed of the tsunami wave front.

This activity uses data collected from DART (Deep-ocean Assessment and Reporting of Tsunamis) stations in the Pacific following the 2011 tsunami generated off the coast of Japan. Based on tsunami arrival times at each DART station, students are required to map the wave front after 5, 10, and 15 hours to better understand the speed and propagation of the tsunami wave. Students are required to estimate when the tsunami would arrive at various locations and then use these estimations to calculate the speed of the wave. At the end of the activity students should understand how tsunami waves propagate across the ocean (roughly circular trajectory), that tsunami are shallow water waves and what this means for calculating the wave speed, and that tsunami, like all waves, are a propagation of energy.

• Student Handout for Tsunami Assignment (Microsoft Word 2007 (.docx) 796kB May21 13)
• Map of Pacific Dart Stations (Acrobat (PDF) 427kB May21 13)

I have found that my students have some trouble plotting the data because they have an incomplete understanding of the concept of a "wave-front." Thoroughly describing this term using examples before the exercise helps.

I listen to the individual groups during the exercise and then lead a full class discussion to qualitatively assess the students' understanding of the assignment. I also collect the assignment from each student to catch any persisting misconceptions after the discussion.

Web Resources:

Information about the 2011 tsunami from NGDC including raw DART data:

http://www.ngdc.noaa.gov/hazard/honshu_11mar2011.shtml

Before and after photos in Japan:

http://www.abc.net.au/news/specials/japan-quake-2011/

Tsunami Debris:

http://marinedebris.noaa.gov/tsunamidebris/