4.3

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reduce Earthquake damage

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4.3

  1. 1. Earthquake Damage can be Reduced
  2. 2. Why do we care about Earthquakes? <ul><li>Earthquakes can cause severe damage and loss of life. </li></ul><ul><li>Earthquakes are most dangerous when the epicenter is near a heavily populated area </li></ul><ul><ul><li>Most injuries are not caused by the movement of the ground. </li></ul></ul><ul><ul><li>They are caused by collapsing buildings and structure fires due to broken natural-gas lines, electrical lines, etc. </li></ul></ul>
  3. 3. Which do you think caused more injuries to people? Recently plowed field, 1979, California Haiti, 2010
  4. 4. Earthquake Magnitude <ul><li>Richter Scale - measures magnitude by how fast the ground moves at a seismic station </li></ul>
  5. 5. Earthquake Magnitude <ul><li>Moment magnitude scale - based on the total amount of energy released by earthquakes; more accurate than Richter for larger earthquakes </li></ul>This information is used to help predict where/when an earthquake is likely to occur
  6. 6. Damage from Earthquakes <ul><li>Aftershock - a smaller earthquake that follows a more powerful earthquake in the same area </li></ul><ul><li>Landslides often occur as a result of earthquakes. </li></ul>
  7. 7. Damage from Earthquakes <ul><li>Liquefaction - a process in which shaking of the ground causes soil to act like a liquid </li></ul>
  8. 8. Damage from Earthquakes <ul><li>Tsunami - a water wave triggered by an earthquake, volcanic eruption, or landslide </li></ul><ul><ul><li>These special waves will rise more than the height of a 20 story building. </li></ul></ul>
  9. 9. Tsunamis <ul><li>Can travel thousands of miles without weakening. </li></ul><ul><li>Can reach speeds of 430 mi/hr. </li></ul><ul><li>In the open ocean the tsunami may only reach about 3 ft. in height. As they get closer to the shore they slow down and gain height. </li></ul>
  10. 10. Scientists work to monitor and predict earthquakes. <ul><li>Scientists cannot yet predict the day or even the year when an earthquake will strike. </li></ul><ul><li>Sometimes there are warning signs, sometimes none at all. </li></ul><ul><li>Scientists give long term predictions. They may state that an area has a 60% chance of having a magnitude 7 or higher earthquake in the next 25 years. </li></ul>
  11. 11. Scientists work to monitor and predict earthquakes. <ul><li>Scientists study seismic activity along faults all over the world. They monitor stress that is building up in rocks. </li></ul><ul><ul><li>Signs of stress buildup </li></ul></ul><ul><ul><li>Tilts or changes in elevation of the ground. </li></ul></ul><ul><ul><li>Slow movements or stretching of rocks. </li></ul></ul><ul><ul><li>Development of small cracks in the ground. </li></ul></ul>

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