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Leaving Certificate Geography Unit 1.4 : Earthquakes

Leaving Certificate Geography Unit 1.4 : Earthquakes. Mr. McMahon. Learning Outcomes . You will learn…. What an earthquake is. Why they occur. How their global pattern is explained by the location of fault lines. . How earthquake zones are located and measured. How they are predicted.

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Leaving Certificate Geography Unit 1.4 : Earthquakes

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  1. Leaving Certificate Geography Unit 1.4 : Earthquakes Mr. McMahon Mr.C.McMahon

  2. Learning Outcomes • You will learn…. • What an earthquake is. • Why they occur. • How their global pattern is explained by the location of fault lines. • How earthquake zones are located and measured. • How they are predicted. • How earthquakes impact upon the landscape and human populations. Mr.C.McMahon

  3. Earthquakes-The Past Ten Years Mr.C.McMahon

  4. What is an Earthquake ? Damage Decreases From Epicentre Scarp Mr.C.McMahon

  5. What Causes Earthquakes? • The plates of the crust are constantly moving. • Sometimes plates jam or stick together. • This creates a build up of energy when one or both plates slip releasing seismic waves that can violently shake the surface above. http://www.youtube.com/watch?v=P53OJd_lxew Mr.C.McMahon

  6. Key Concepts • Focus: The point where an earthquake begins in earth’s crust. Earthquakes can be shallow or deep focus. • Epicentre: The point on the surface that is the worst affected by a quake. Damage lessens the further one moves from the epicentre. Mr.C.McMahon New Zealand Earthquake 2011

  7. The Global Distribution of Earthquakes Mr.C.McMahon

  8. Location of Earthquakes • Earthquakes do no occur randomly. • Their location is based on plate boundaries. • Earthquakes occur at convergent, divergent and transform boundaries. Mr.C.McMahon

  9. The Subduction zone of Japan is the most earthquake prone area in the world. • Transform Fault. California USA. • Rifting: East Africa • Divergent: Mid Atlantic Ridge. • Convergent: Columbia -Chile Mr.C.McMahon

  10. Seismic waves • Primary (P) waves: Fast waves that compress then expand molten material • http://www.youtube.com/watch?v=_YLjIvJXhpg Mr.C.McMahon

  11. Secondary (S) waves are slow as they have to travel through solid rock. Mr.C.McMahon

  12. Earthquake Waves Mr.C.McMahon

  13. Surface Waves: The slowest waves that expend their energy on the surface causing anything on it to move up and down. • Principle.Energy from waves is absorbed by material as it travels through them. Thus the father a wave travels the more energy they expend. Mr.C.McMahon

  14. Measuring Earthquakes • The Seismograph • Three are needed for a full set of data • Horizontal measuring waves North-South • Horizontal- East to West. • Vertical Movement Mr.C.McMahon

  15. The Richter Scale • Logarithmic Scale. • Each unit is 10 times the wave activity of the previous for example a force 8 is 10 times greater than a force 7. • The force is measured at a greater rate of 30. http://www.youtube.com/watch?v=1qbg7orb1lc Mr.C.McMahon

  16. Predicting Earthquakes • Earthquake zones are identified. • Predictions based on timeframes. • Seismologist Identify seismic gaps- points between plates where earthquakes are likely to begin. Mr.C.McMahon

  17. Early Warning Systems • Early Warning systems based on modern communication systems are being developed. • Monitoring animal behaviour. Mr.C.McMahon

  18. Mr.C.McMahon

  19. Destruction by Earthquakes • Destruction by earthquakes depends on the following. • The depth of the focus • The population density around the epicentre. • Economic development and the standard of buildings. • Overlying Topography Mr.C.McMahon

  20. Soil Liquefaction • Liquefaction is the process of soil, clay and sand turning into a sludge. • During an earthquake ground water mixes with the soil types to produce a material like quicksand. • This undermines the foundations of bridges, roads, dams etc…. • Consequences ? Mr.C.McMahon

  21. Other Dangers • Falling Debris • Flooding • Burst gas and sewage mains. • Spread of disease • Disruption to emergency services • Tsunamis Mr.C.McMahon

  22. Tsunami • Giant waves that are generated when an earthquake occurs on the sea floor. • See Indian ocean Earthquake- Tusnami animation Wikipedia Mr.C.McMahon

  23. Limiting Earthquake Damage • Retro- fitting of Old Buildings. • The development of advanced warning systems • Tapered frames to increase a buildings frames integrity • The use of shock absorbers in a buildings columns and foundations. Mr.C.McMahon

  24. Case Study: The Haiti Earthquake • Tuesday 12th January 2010. • Measured 7.0 Richter Scale • Focus at 13 KM • Epicentre 13KM from the capital Port Au Prince www.bigpicture@boston.comHaitiearthquake Mr.C.McMahon

  25. Haitian Earthquake Map http://www.youtube.com/watch?v=1IzEYHetFUE Mr.C.McMahon

  26. Case Study: The Japan Earthquake • Struck on March 11th 2010 • Richter Scale 9.0 • Epicentre 60KM from the coast triggered Giant Tsunami • Over 12,690 dead and 14,000 unaccounted for. http://www.youtube.com/watch?v=3Uq2hA2-9oc Mr.C.McMahon

  27. http://www.youtube.com/watch?v=hOe8PMoKdI8 Japan Earthquake Map Mr.C.McMahon

  28. Key Concepts • Earthquake • Focus • Epicentre • Seismology • Seismograph • Richter scale • Magnitude • P Waves • Q Waves • S Waves • Earthquake Prediction • Early Warning Systems • Scarp • Tsunami • Tremor • Aftershocks Mr.C.McMahon

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