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Earthquake 1

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  • 1. NATURAL DISASTER Objectives Main Menu Earthquake Credits Natural Disaster Prior Knowledge Resources Tropical Cyclone Case study: Cyclone in Bangladesh Evaluation
  • 2. Click the picture to start
  • 3. Click the picture to start
  • 4. OBJECTIVES To define natural disaster To list down the four different types of natural disaster To explain the causes of an earthquake and tropical cyclone To list down the effects/problems causes by an earthquakes and tropical cyclone To describe measures to minimize the damages caused by an earthquake and tropical cyclone
  • 5. Prior Knowledge The three layers of the Earth’s structure : core, mantle, and crust. The plates movements and its boundaries, and the distribution of the world's volcanic and earthquake areas. The students must have some background knowledge of the followings:
  • 6. NATURAL DISASTER DIFFERENT TYPES OF NATURAL DISASTER DEFINITION OF NATURAL DISASTER
  • 7. WHAT IS A DISASTER? A DISASTER IS AN EVENT WHICH BRINGS GREAT TROUBLE AND HARDSHIP NATURAL DISASTER OCCURS BECAUSE OF UNUSUAL MOVEMENTS OF THE EARTH, WIND, OR WATER
  • 8.
    • Earthquake
    • Tropical storm
    • Drought
    • Floods
    • Volcanic eruption
    The different types of natural disaster are:
  • 9. EXAMPLES OF NATURAL DISASTER EARTHQUAKES
  • 10. TROPICAL STORMS EXAMPLES OF NATURAL DISASTER
  • 11. DROUGHTS EXAMPLES OF NATURAL DISASTER
  • 12. EXAMPLES OF NATURAL DISASTER FLOODS
  • 13. EXAMPLES OF NATURAL DISASTER VOLCANIC ERUPTION
  • 14. EARTHQUAKE What is an earthquake? Earthquake zones around the world Effects and problems caused by an earthquake Terms related to an earthquake Minimizing the damage caused by an earthquake
  • 15. What is an earthquake?
    • An earthquake is a sudden movements of the Earth’s crust.
    • Earthquakes are caused either by two plates moving against each other or when two plates moving towards each other .
  • 16. Earth’s Crustal Plates One plate sometimes moves against another and this often puts a great strain on the rocks that they tear at the weakest point
  • 17.
    • Earthquakes also occur when two plates moves towards each other .
    • The movement has result in the formation of fold mountains, volcanoes and earthquakes.
    • This explains why earthquakes, fold mountains and volcanoes are often found together .
  • 18. Terms related to an earthquake
    • Seismic focus is the point in the Earth’s crust where an earthquake originates.
    • Epicentre is the point on the Earth or sea’s surface which receives the strongest waves. It is directly above the seismic focus.
    • Isoseismal lines are lines joining places receiving shock waves of equal intensity.
    • The amount of energy released is measured by delicate instruments called seismometers .
    • Richter scale is a magnitude number used to measure the ground motion on seismometer. This scale has no upper limit, but the most sever earthquakes have reached a magnitude of 8.9.
  • 19. Isoseismal lines Seismic focus Epicentre
  • 20. Seismometers
  • 21. Richter Scale
  • 22. Earthquake zones around the world
  • 23. Effects and problems caused by an earthquake
    • Earthquakes which occur on or under the sea bed can cause tidal waves or Tsunami , which can reach speeds of 600 to 800 km per hour and heights of 60 meters.
    • In 1983, over 50 people were killed by Tsunami waves which struck the north-west coast of Japan.
  • 24. Tsunami
  • 25. Tsumani Wave A tsunami wave flows toward the shore after a small earthquake in the Sunda Strait of Indonesia. Tsunamis are often mistakenly called tidal waves, but they are not caused by the gravitational forces involved in tides. Instead, tsunamis are believed to be caused by a tilting of the ocean floor, undersea landslides, or undersea volcanic eruptions
  • 26. Effects and problems caused by an earthquake Each year about 500,00 earthquakes are recorded and of these about 1000 are strong enough to cause damage. As a result of these, roads and railways twist and buckle. Sewers, gas and water pipes and electricity cables break. Buildings crack and fall down. In the worst earthquakes, whole towns have been destroyed, and many people killed or injured.
  • 27. Twisted and buckled roads
  • 28. Sewers, gas, water pipes, and electricity cables break
  • 29. Buildings crack and fall down
  • 30.
    • No one can prevent an earthquake. However, steps can be taken to minimise the loss of lives and damage to property.
    • Below are some of the measures taken to mininise the damaged caused by an earthquake:
    • New buildings are designed to withstand earthquake shocks
    • In earthquake zones, new building are placed on solid rock. They have a framework of strong flexible steel.
    • Tall buildings are not built in high-risk areas.
    Minimising damage from earthquakes Click next/here to continue
  • 31. Minimising damage from earthquakeS
    • The streets are made wide so that building will not block them if they fall.
    • Open spaces are left in towns, so that people can go to them out of reach of falling buildings.
    • People can be trained to know what to do should an earthquake occur and towns should have trained people, equipment, medical and food supplies, to organize the evacuation of the people.
    • Scientists, with their seismometers and many other delicate instruments, monitor the situation day and night.
  • 32. TROPICAL CYCLONES What are tropical cyclones? Names given to tropical storms Where do tropical cyclone born? Case Study: Tropical cyclones in Bangladesh Tropical cyclone around the world How tropical cyclone is formed? How do tropical cyclone gains its energy?
  • 33.
    • Tropical cyclones are intense low-pressure centres to which winds blow in a spiral movement with wind speeds up to 200km per hr along with violent thundery rainfall.
    • It has a calm, clear eye in the middle and moves over hundreds km in a day.
    What are Tropical Cyclones ? Click next/here to continue
  • 34.
    • Meteorologists use satellite images taken in infrared light to determine the heat of areas of the atmosphere. The data is translated into a visible image, which is often enhanced, or colored with shades representing temperatures. In enhanced images, red usually represents the hottest temperatures and violet usually represents the coolest temperatures.
    Infrared Image of Hurricane
  • 35.
    • Tropical cyclone around the world
    • In the Atlantic Ocean and Caribbean sea known as hurricanes .
    • In the Pacific, along the coast of China, Japan and the Philippines known as typhoons
    • In the Indian ocean and Bay of Bengal known as cyclones
    • In Australia it is known as Willy-willies
    What are other names of tropical cyclones ?
  • 36. TROPICAL CYCLONE AROUND THE WORLD
  • 37.
    • They are born over the oceans, between latitudes 5  and 15  North and South, where the sea temperatures are over 27  C
    Where do Tropical cyclones born ?
  • 38. Tropical cyclones are born over the oceans, between latitudes 5  and 15  North and South
  • 39.
    • It is formed when air becomes warm and begin to rise. Minute water droplets form on the rising air. They make huge cumulo-nimbus clouds which hold thousands of tones of water. They can reach 15km high.
    How Tropical cyclones are formed ?
  • 40. FORMATION OF CUMULO-NIMBUS CLOUD
  • 41. CUMULO-NIMBUS CLOUD
  • 42.
    • The main energy source for a tropical cyclone is the latent heat released by the condensation from warm moist air.
    • After a week or so, the cyclone reaches cooler seas or land. It then loses energy and dies out.
    How do these cyclones gain the energy?
  • 43. Formation of Tropical Cyclone
    • Tropical cyclones form over water when a mass of thunderstorms becomes organized and spirals in toward the storm’s center, or eye. The storm’s highest winds, strongest thunderstorms, and heaviest rain, occur just outside the eye in the region called the eye wall. In the eye itself, winds are usually light and skies are partly cloudy.
    • Tropical cyclones derive their energy from the transfer of heat from the warm water and from the latent heat given up to the system during condensation. Tropical cyclones dissipate when they are cut off from their energy sources either by moving over cold water or a large land mass. Although tropical cyclones often take erratic paths, the prevailing easterly winds in the tropics tend to steer tropical cyclones westward or northwestward until they leave the tropics, then the prevailing westerlies tend to sweep them northeastward.
  • 44. Case Study: TROPICAL CYCLONES IN BANGLADESH How do tropical cyclone bring disaster to Bangladesh? 1991 Cyclone In Bangladesh How did the cyclone been spotted? The worst affected areas hits by the cyclone in Bangladesh Problems caused by tropical cyclone
  • 45. The worst affected areas hits by the cyclone in Bangladesh
  • 46.
    • The tropical cyclones in the Bay of Bengal bring disaster to the coastal regions of India and Bangladesh .
    • The strong winds trap the high tide water and form giant storm waves, sometimes 25 m high, carrying all before them.
    How do the cyclones bring disaster to Bangladesh?
  • 47. These giant strong waves cause many deaths on the low coastal plains and offshore island
  • 48.
    • On the night of 29 April 1991, the most powerful cyclone to hit Bangladesh in its 20 year history tore through coastal areas and offshore island after 10pm and lasted for seven hours.
    • More than 15 million people were homeless, and nearly 150,000 people were killed.
    1991 Cyclone in Bangladesh
  • 49.
    • The cyclone had been spotted out in the Bay of Bengal by a weather satellite on 23 April 1991.
    • Satellites can track tropical cyclones and warning can be given to areas that lie in their path.
    • Government issued alerts and warning to the people.
    How did the cyclone been spotted?
  • 50.
    • Most weather services use satellite information in their forecasts. Pictures such as this one of Hurricane Gloria reveal patterns and movement that provide clues about what the storm might do next. The weather is continuously monitored and photographed by satellites worldwide, but it is still difficult to predict weather because of the many variables involved. Infrared sensors help meteorologists to interpret the pictures by determining the height and temperature of the clouds.
    Weather Satellite
  • 51.
    • The government had issued warnings on the radio and television.
    • The local Red Crescent and trained volunteers were also alerted.
    Government Issued Alert on the Cyclone
  • 52.
    • The worst affected area was between Chittagong and Cox’s Bazaar along the coast, and the off-shore islands of Sandwip, Kutubdia and Maheshkali.
    • The whole densely populated area was covered by tidal wave.
    The worst affected areas hits by the cyclone in Bangladesh
  • 53. PROBLEMS CAUSED BY TROPICAL CYCLONES -WITH REFERENCE TO THE BANGLADESH GOVERNMENT
    • The winds and waves battered the coastal areas for about four hours.
    • The cyclone destroyed crops, huts, roads, bridges and electricity pylons.
    • The salt water destroyed rice harvests and contaminated drinking water.
    • Life after the cyclone was more difficult without food, drinking water and shelter.
  • 54. PROBLEMS CAUSED BY TROPICAL CYCLONES PROBLEMS CAUSED BY TROPICAL CYCLONES -WITH REFERENCE TO THE BANGLADESH Measures to minimize the problems of tropical cyclone in Bangladesh
  • 55. Measures to minimize the problems of tropical cyclone in Bangladesh
    • More than 120,000 were killed and millions left homeless in April 1991 when a powerful cyclone struck the coastal areas in the Ganges delta.
    • Little could be done to solve problem of tropical cyclone in Bangladesh, nevertheless, aids, in the form of money, medicines, food, clothing, shelters, doctors, nurses and other voluntary workers came to Bangladesh through the United Nation and from individual countries and organization.
    • Countries are learning to co-operate speedily in times of disaster and to share their wealth and expertise however, more must be done to help to protect the people from natural disasters.
  • 56.
    • 1. Encarta Reference Library 2002 – Full Retail.
    • 2. World Book Deluxe Edition 1999.
    • 3. Valentine F. and R. B. Bunnett, “ Interactive Geography 3 ”, Pan Pacific Publications (S) Pte. Ltd. 2001,
    • 4. Secondary Geography 3, Brunei Darussalam.
    RESOURCES:
  • 57. 1.Multiple Choice 2.Cross word puzzle 3. Fill in the Blanks 4. Matching exercises Evaluation
  • 58. http://msnbcmedia.msn.com/i/msnbc/Components/Interactives/Technology_Science/Science/Earthquakes/zFlashAssets/Earthquakes_v21.swf

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