Name: ___Tiffany Rodriguez Learning Unit 5: Tsunami Review Questions This assignment is designed to assess your understanding of Unit 5 and includes some of the Questions for Review at the end of Chapter 5 from your text plus a few additional questions. Each question can be answered in one to two sentences. Please limit yourself to a maximum of three sentences. Access the assignment, complete it with ANSWERS IN A DIFFERENT COLOR FONT as a separate file, and send it back for evaluation and grading through the assignment tab by or before the due date. 1. How many tsunami waves are generated when an abrupt disturbance, such as an earthquake, vertically displaces the water column? A tsunami is a series of wave, often referred to as a “wave train’. They can come in a series ,one after another and take up to an hour to finish. 2. Of the three main types of fault movements—strike-slip faults, normal faults, and reverse (thrust) faults—which can and which cannot cause tsunami? Why? Strike-slip cannot cause tsunami. The main reason is because there is no vertical displacement within the fault movement. It only moves back and forth or side to side. Normal and thrust faults let the water rise up and then when it comes back down the water that is displaced is what causes the wave fro the tsunami. 3. How dangerous are tsunami waves in the open ocean? And why? In Open ocean tsunamis waves are law and far apart and they move fast. Some waves can move up to several hundred kilometers per hours which can maek them harder to see and increase their danger levels. 4. Which is the more dangerous location for a tsunami, a straight stretch of open coast or a bay? Why? The tsunami would be more dangerous in the open ocean since there is nothing that can stop the waves while in a bay they will gradually slow down. 5. What is often the first indication of the arrival of a tsunami at the coast? The rapid drop in sea level. 6. For a subduction-zone earthquake off the coast of Oregon or Washington, how long would it take for a tsunami wave to first reach the coast? It would take less than 20 minutes to reach the coast. 7. What are the approximate times between tsunami wave crests? The approximate times are 10 to 35 minnutes or on average about 30 minutes. 8. Which wave of a major tsunami is likely to be the highest – first, fourth, tenth? The fourth is most likely to be the highest. 9. In December, 2004, a pair of closely related natural disasters killed tens of thousands of people. (Case in Point: Lack of Warning and Education Costs Lives, Sumatra Tsunami, 2004) a. What was the initial event (not the one that killed most of the people)? The major earthquake b. Where, specifically, was that initial event? It was off the southwest coast of sumatrac. What secondary event (the one that killed most of the people) was caused by the initial event noted above? A tsunami d. Explain (concisely and in detail) exactly how the initial event was related to the secondary event? The earthquake was the start while it created the tsunami which was the real tragedy. 10. There have not been any very large earthquakes on the subduction zone of the coast of Washington and Oregon in hundreds of years. Explain why not and what are the implications based on records of past events. The subduction zone is locke and the last majojr earthquake was in 1700. Ginat earthquakes happen every few hundred yearts and the next major one could come at any time. 11. On low-lying coastal flats near Anchorage, Alaska, the foundations of buildings dropped below sea level during the giant 1964 earthquake. Decades later, their foundations are again above sea level. (Case in Point: Subduction Zone Earthquake Generates a Major Tsunami) a. What type of tectonic boundary caused the earthquake, and what plate motions are involved? Subduction zone boundary. While it was locked the ocean floor pulled down the edge of the continental margin causing it to slowly bivkle up. b. Explain what tecontic forces led to the ground sinking and later rising. The pacific ocean floor was descending under the continental margin and since the release of the coundary during the earthquake permitted the grount to drop so suddenly the sea moved in and decades later the edge of the continent is again rising since the subduction zone is again locked. 12. What type of event has repeatedly generated high tsunami waves in Lituya Bay of southeastern Alaska? Be specific. (Case in Point: Immense Local Tsunami from a Landslide, Lituya Bay, Alaska, 1958) When major fast moving rockfall or Landslide enter the ocean. They can displace large amounts of water and generate tsunamis. 13. List some of the ways volcanoes can generate tsunami. Some ways is by the process that displaces large volumes of water including -Volcanic earthquakes - Undersea eruptions -Pyroclatic flows -Caldera collapse -Landslides -Lahars 14. How are tsunami waves in the Atlantic Ocean likely to be generated? They are created by subduction-zone earthquakes and landslides into the ocean. 15. Why are even good swimmers often killed by tsunami waves?Really good swimmer are usually killed by tsunamis because they become trapped in string current or can be struck and killed by large
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