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Earthquakes
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  • 1. © Boardworks Ltd 20051 of 37 These icons indicate that teacher’s notes or useful web addresses are available in the Notes Page. This icon indicates the slide contains activities created in Flash. These activities are not editable. For more detailed instructions, see the Getting Started presentation. 1 of 37 © Boardworks Ltd 2005 Earthquakes
  • 2. © Boardworks Ltd 20052 of 37 What are earthquakes and where do they occur? What causes earthquakes? How are earthquakes measured? What is the difference between the epicentre and the focus? How can we limit the damage caused by earthquakes? What is a tsunami? Learningobjectives
  • 3. © Boardworks Ltd 20053 of 37 What are earthquakes? They can occur at all four major plate boundaries but the most severe earthquakes are normally found at conservative and destructive plate boundaries. conservative destructive Earthquakes are vibrations caused by earth movements at plate boundaries and at major fault lines (cracks in the earth’s surface).
  • 4. © Boardworks Ltd 20054 of 37 Destructive plate boundary
  • 5. © Boardworks Ltd 20055 of 37 Conservative plate boundary
  • 6. © Boardworks Ltd 20056 of 37 What are earthquakes and where do they occur? What causes earthquakes? How are earthquakes measured? What is the difference between the epicentre and the focus? How can we limit the damage caused by earthquakes? What is a tsunami? Learningobjectives
  • 7. © Boardworks Ltd 20057 of 37 Why do earthquakes happen?
  • 8. © Boardworks Ltd 20058 of 37 What are earthquakes and where do they occur? What causes earthquakes? How are earthquakes measured? What is the difference between the epicentre and the focus? How can we limit the damage caused by earthquakes? What is a tsunami? Learningobjectives
  • 9. © Boardworks Ltd 20059 of 37 How can we measure earthquakes? This measures the magnitude of a tremor (how powerful it is) using an instrument called a seismograph. On the Richter Scale, magnitude is expressed in whole numbers and decimal fractions. Although the Richter Scale has no upper limit, the largest earthquake ever recorded was in 1960 in Chile. It measured 9.5 on the Richter Scale. It is a logarithmic scale which means that a size ‘6’ on the Richter Scale is 10 times larger than a size ‘5’ and 100 times larger than a size ‘4’. The Richter Scale
  • 10. © Boardworks Ltd 200510 of 37 How many times greater was the Japanese earthquake? How can we measure earthquakes? The Japanese earthquake was 10 times more powerful than the Greek earthquake. The Japanese earthquake in Kobe (September 1995) measured 7.2 on the Richter Scale. The Greek earthquake (June 1995) measured 6.2 on the Richter Scale.
  • 11. © Boardworks Ltd 200511 of 37 A seismograph
  • 12. © Boardworks Ltd 200512 of 37 Mercalli Scale The Mercalli scale measures how much damage is caused by the earthquake based on observations. It is measured on a scale between 1 and 12. Mercalli Scale
  • 13. © Boardworks Ltd 200513 of 37 I Felt by almost no one. II Felt by very few people. III Tremor noticed by many, but they often do not realise it is an earthquake. IV Felt indoors by many. Feels like a truck has struck the building. V Felt by everyone; many people are awakened. Swaying trees and poles may be observed. VI Felt by all; many people run outdoors. Furniture is moved. VII Everyone runs outdoors. Poorly built structures considerably damaged. Slight damage elsewhere. VIII Specially designed structures damaged slightly, others collapse. IX All buildings considerably damaged, many shift off foundations. Noticeable cracks in the ground. X Many structures destroyed. Ground badly cracked. XI Almost all structures fall. Bridges wrecked. XII Total destruction. Waves seen on ground surfaces. Activity Design your own cartoon based on the Mercalli Scale descriptions below.
  • 14. © Boardworks Ltd 200514 of 37 What are earthquakes and where do they occur? What causes earthquakes? How are earthquakes measured? What is the difference between the epicentre and the focus? How can we limit the damage caused by earthquakes? What is a tsunami? Learningobjectives
  • 15. © Boardworks Ltd 200515 of 37 Epicentre and focus The focus is the point at which the rock moves. Seismic waves start at the focus. The epicentre is directly above the focus on the earth’s surface.
  • 16. © Boardworks Ltd 200516 of 37 Epicentre and focus
  • 17. © Boardworks Ltd 200517 of 37 Focus Epicentre An earthquake has occurred along this fault line. Match the letter with the correct label. Epicentre and focus
  • 18. © Boardworks Ltd 200518 of 37 An earthquake has occurred in this area. Which area (the town or the forest) will receive the stronger earthquake? Which area will receive more damage from the earthquake? Epicentre and focus
  • 19. © Boardworks Ltd 200519 of 37 If the epicentre of an earthquake is at ‘A’, which settlement will be damaged the most? Give reasons for your answer. Epicentre and focus
  • 20. © Boardworks Ltd 200520 of 37 What are earthquakes and where do they occur? What causes earthquakes? How are earthquakes measured? What is the difference between the epicentre and the focus? How can we limit the damage caused by earthquakes? What is a tsunami? Learningobjectives
  • 21. © Boardworks Ltd 200521 of 37 predict plan protect Predict water levels can rise in wells and lakes because of cracks in the rock foreshocks before the main quake can be detected by a seismometer animals can act strangely before the earthquake a tiltmeter can check any movement within the rocks How can we limit earthquake damage?
  • 22. © Boardworks Ltd 200522 of 37 Plan and protect How can we limit earthquake damage?
  • 23. © Boardworks Ltd 200523 of 37 What should people pack in their emergency kit? Design a poster reminding people what to do in an earthquake. How can we limit earthquake damage? Plan and protect
  • 24. © Boardworks Ltd 200524 of 37 What other measures would make buildings less likely to collapse in an earthquake? Building regulations in earthquake zones
  • 25. © Boardworks Ltd 200525 of 37 Which shape of building would be most ‘earthquake proof’? Explain your answer. Buildings in earthquake zones
  • 26. © Boardworks Ltd 200526 of 37 This is San Francisco in the USA. San Francisco is near the San Andreas Fault and therefore the city experiences earthquakes. Building in earthquake zones This skyscraper has been built to be ‘earthquake-proof’. Its wide base lowers the centre of gravity of the building and makes it more stable.
  • 27. © Boardworks Ltd 200527 of 37 This is Sky Tower in Auckland, New Zealand. Sky Tower is the tallest tower (328 metres) in the Southern Hemisphere. It weighs 21 million kilos (20,000 tonnes), which is equivalent to 6,000 elephants! Auckland is in an earthquake zone and so the tower is constructed from a high strength, high performance concrete. Sky Tower's foundations go down more than 15 metres. Sky’s the limit!
  • 28. © Boardworks Ltd 200528 of 37 Turkish earthquake (August 1999) Fact File (3 days after the earthquake) Dead : 10,059 Missing : up to 35,000 Injured : over 45,000
  • 29. © Boardworks Ltd 200529 of 37 Turkish earthquake (August 1999)
  • 30. © Boardworks Ltd 200530 of 37 Factors affecting the damage caused by earthquakes size of the earthquake time of day emergency services building design and construction education physical landscape 1) Which factor/s do you think is/are the most important? 2) Which factors are related to the wealth of the country? 3) How can the education of the population affect the amount of damage caused by an earthquake?
  • 31. © Boardworks Ltd 200531 of 37 Read the following two slides. Compare the earthquake in Los Angeles (94) with the earthquake in Turkey (99) using the following table (you will need an atlas to help with your research). size of the earthquake time of day emergency services building design and construction GNP (wealth) number of deaths education Los Angeles Turkey Factors affecting the damage caused by earthquakes
  • 32. © Boardworks Ltd 200532 of 37 Los Angeles earthquake (1/94)
  • 33. © Boardworks Ltd 200533 of 37 Turkey earthquake (8/99)
  • 34. © Boardworks Ltd 200534 of 37 What are earthquakes and where do they occur? What causes earthquakes? How are earthquakes measured? What is the difference between the epicentre and the focus? How can we limit the damage caused by earthquakes? What is a tsunami? Learningobjectives
  • 35. © Boardworks Ltd 200535 of 37 SE Asian tsunami – December 2004 Tsunamis are tidal waves triggered by underwater earthquakes. The rate of travel of a tsunami is between 400- 600 miles per hour. The tsunami in SE Asia occurred on the 26th December 2004. The earthquake measured 9.0 on the Richter Scale and occurred off the northern tip of Sumatra. The tsunami spread across the Indian Ocean and hit coastal areas of Sri Lanka, India, Bangladesh, Myanmar, Indonesia and Malaysia. The death toll is believed to be 290,000.
  • 36. © Boardworks Ltd 200536 of 37 Where was the tsunami?
  • 37. © Boardworks Ltd 200537 of 37 What caused the tsunami?