Tsunamis: Ocean and Wave Shape Changes
6 05 Tsunami Nicolai Kortendick 1. The web site presents extensive information regarding tsunamis. Survey the site. A. Select the five facts about tsunamis that were the most interesting or surprising to you. Make a list of your facts. 1. A tsunami is made up of a series of traveling ocean waves of extremely long wavelength. 2. They are triggered by earthquakes and undersea volcanic eruptions and deep sea landslides. 3. The wave shape changes and the height increases as it approaches the coastline. . Far field tsunamis have a long travel time so it is easier to predict their effects. 5. Near field tsunami have a travel time of one or two hours, making it harder to evacuate people to safe, high areas before the tsunami reaches the coast. B. Now look over your list. In your opinion, what is the most intriguing item on your list? Explain. The most intriguing item on the list to me is that tsunamis resemble waves that I see a lot every day and they have extremely long wavelengths. 2.
If you were on a ship at sea, and a tsunami passed under your ship, what would probably be your reaction? Explain. I would be pretty scared if I knew it was a tsunami, and I would be worried for the people on the coast it was heading for. It probably wouldn’t be a very big wave if I was far out in the ocean so it wouldn’t scare me as much. 3. The site offers a tsunami quiz. Take the quiz. What was your score? I got 7 out of the 10 questions correct. 4. When you viewed the “Introduction to Waves” video, you learned several terms that apply to all waves.
How do the following terms apply to tsunamis and what are typical values for a tsunami’s wavelength and amplitude? Use the following sites to look for answers: http://www. enchantedlearning. com/subjects/tsunami http://hyperphysics. phy-astr. gsu. edu/HBASE/Waves/tsunami. html C. Wavelength Tsunamis have an extremely long wavelength (which is the distance between the crest of one wave and the crest of the next wave) – up to several hundred miles long. D. amplitude
The amplitude of a wave is the height of a wave from the still water level to the top of the wave crest. As a tsunami reaches a coastline its amplitude increase greatly. E. crest The crest is the top of a wave. The wavelength of a wave is measured from the crest of one wave to the crest of another. F. trough The trough is the bottom of a wave. As a tsunami approaches the coast (where the sea becomes shallow), the trough of a wave hits the beach floor, causing the wave to slow down, to increase in height and to decrease in wavelength.