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Tsunamis

Tsunamis. EPS 131 Introduction to Physical Oceanography. Presented by: Saira Hashmi Oct. 14 th ,2005. Overview. Tsunami - what is it? Tsunami Formation What is the Physics behind them? Warning systems? Examples of Tsunamis Animations/Simulations Conclusion References Questions.

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Tsunamis

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  1. Tsunamis EPS 131Introduction to Physical Oceanography Presented by: Saira Hashmi Oct. 14th,2005

  2. Overview • Tsunami - what is it? • Tsunami Formation • What is the Physics behind them? • Warning systems? • Examples of Tsunamis • Animations/Simulations • Conclusion • References • Questions

  3. Tsunami- what is it? Definition: • Unusually large wave in a harbour (Japanese) • Series of water waves generated by huge and sudden perturbation (e.g. earthquakes, slides, volcanoes, asteroids) Characteristics: • Wave period: 2-200 minutes • Run-up heights: O(10-100 m)(Flooding of shoreline) • Speed

  4. Tsunami Formation

  5. Tsunami Formation • Tsunamis can be generated when the sea floor suddenly displaces the overlying water vertically. • Tectonic earthquakes are a kind of earthquake that can cause that. • When they occur beneath the sea, the water above the deformed area is displaced from its equilibrium position. • Waves are formed as the displaced water mass, acting under the force of gravity, tries to regain equilibrium. • When large areas of the sea floor elevate or subside, a tsunami can be created. • Large vertical movements of the earth's crust can occur at plate boundaries, at the faults.

  6. Tsunami Formation • As a tsunami leaves the deep ocean and travels toward the shallow coast, it transforms. • A tsunami moves at a speed related to the water depth, therefore the tsunami slows as the water depth decreases. • The tsunami's energy flux, being dependent on both its wave speed and wave height, remains nearly constant. • As a result, the tsunami's speed decreases as it travels into shallower water, and its height increases. • When it reaches the coast, it may appear as a rapidly rising or a series of breaking waves.

  7. Tsunami Formation • As a tsunami reaches the shore, it begins to lose energy . • It Slows down and height increases when approaching shallow coast • Tsunamis reach the coast with tremendous amounts of energy. • Destructive power is due to speed and force with which they strike the coastal area. • Tsunamis are stronger and retain height longer than waves generated by wind.

  8. What’s the Physics behind the Waves……… http://observe.arc.nasa.gov/nasa/exhibits/tsunami/tsun_hit2.html

  9. Warning Systems

  10. PUBLIC WARNING SYSTEMcan you tell if a tsunami is coming? • The U. S. ESSA operates warning systems. • Its PTWC in Hawaii is the regional operational center for tsunami information in the Pacific • A Tsunami Watch Bulletin is released when an earthquake occurs with a magnitude of 6.75 or greater on the Richter scale. • A Tsunami Warning Bulletin is released when information from tidal stations indicates that a potentially destructive tsunami exists. • This system is not very reliable. For example, Honolulu was evacuated in 1948 on a false alarm at a cost of more than $30 million dollars.

  11. Examples of Tsunamis

  12. Simulations/ Animations

  13. Wave Propagation simulation http://www.pgc.nrcan.gc.ca/press/images/2003JB002521-animation.gif

  14. Conclusion Tsunamis….. • Are uncontrollable phenomenon • Causes extensive loss of life • Damage property • Public warning systems provide some measures of protection.

  15. Reference • [Online] . http://pubs.usgs.gov/publications/text/historical.htm [1 February 2005] • "Elastic Rebound" . "Pacific Earthquake Engineering Research Center" . [Online] . http://peer.berkeley.edu/~jrodgers/EQDef/eqdef2.htm [5 March 2005] • "2004 Indian Ocean earthquake" . "Wikipedia" . [Online] . http://en.wikipedia.org/wiki/2004_Indian_Ocean_Earthquake [20 February 2005] • "Tsunami" . "Wikipedia" . [Online] . http://en.wikipedia.org/wiki/Tsunami [20 February 2005] • "USGS Earthquake Hazards Program-Latest Earthquakes" . "US Geological Survey" . [Online] . http://earthquake.usgs.gov/eqinthenews/2004/usslav/ [5 March 2005] • "26 December 2004 Tsunam" . "National Institute of Oceanography, India" . [Online] . http://www.nio.org/jsp/tsunami.jsp [5 March 2005] • "Tsunami!: The WWW Tsunami Information Resource" . "Earth and Space Sciences (Geology and Geophysics) at UW" . [Online] . http://www.ess.washington.edu/tsunami/toc.html [5 March 2005] • "Sumatra Earthquake 26 December 2004" . "British Geological Survey" . [Online] . http://www.earthquakes.bgs.ac.uk/latest_info.htm ] • "USGS Earthquake Hazards Program-Latest Earthquakes" . "US Geological Survey" . [Online] . http://earthquake.usgs.gov/eqinthenews/2004/usslav/ [5 March 2005] • "26 December 2004 Tsunam" . "National Institute of Oceanography, India" . [Online] . http://www.nio.org/jsp/tsunami.jsp [5 March 2005] • "Tsunami!: The WWW Tsunami Information Resource" . "Earth and Space Sciences (Geology and Geophysics) at UW" . [Online] . http://www.ess.washington.edu/tsunami/toc.html [5 March 2005] • "Sumatra Earthquake 26 December 2004" . "British Geological Survey" . [Online] . http://www.earthquakes.bgs.ac.uk/latest_info.htm

  16. Questions

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