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Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
Chapter 2   Earthquakes
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Chapter 2 Earthquakes

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  1. The Changing Earth Chapter 2: Earthquakes
  2. Section 2.1 Earthquakes Occur Along Faults
  3. Continued – See page 46
  4. Rocks move along faults. <ul><li>The lithosphere contains huge breaks (faults) where movement of rock occurs. </li></ul><ul><li>Movement can be slow or fast, or may stop if the two sides lock together. </li></ul><ul><li>The pressure of the rocks causes stress to build up. </li></ul><ul><li>T h e stored energy is released and causes an earthquake – sudden ground motion. </li></ul>
  5. Faults are classified by how rocks move. <ul><li>Normal Fault: a block of rock above the fault plane moves down relative to the other block. Caused by two rocks pulling apart. </li></ul>
  6. Continued – See page 48 <ul><li>Reverse Fault: the block above the fault plane moves up relative to the other block. Caused by the two blocks of rock being pushed together. </li></ul>
  7. Continued – See page 49 <ul><li>Strike-slip Fault: the blocks of rock move horizontally on either side of the fault plane. Caused by rocks being pushed horizontally. </li></ul>
  8. Section 2.2 Earthquakes Release Energy
  9. Energy from earthquakes travels through Earth. <ul><li>Focus: underground location where earthquake begins. </li></ul><ul><ul><li>The crust breaks at the focus. </li></ul></ul><ul><ul><li>Released energy radiates outward in ALL directions. </li></ul></ul><ul><ul><li>Energy is in the form of seismic waves. </li></ul></ul><ul><li>Epicenter: the point on the Earth’s surface directly above the focus. </li></ul>
  10. Continued – See page 52
  11. Continued <ul><li>Three types of seismic waves: </li></ul><ul><ul><li>Primary: travel the fastest and therefore arrive first at any location. They can travel through any material. </li></ul></ul><ul><ul><li>Secondary: travel more slowly than primary waves and arrive second. They do not travel through liquids or gases. </li></ul></ul><ul><ul><li>Surface: travel along the surface of the crust and cause the most damage. They arrive last. </li></ul></ul>
  12. Seismic waves can be measured. <ul><li>Seismograph: instrument used to detect and record ground movements. </li></ul><ul><ul><li>The shaking is recorded on paper or magnetic tape. </li></ul></ul><ul><ul><li>Some record horizontal movement and others record vertical movement. </li></ul></ul><ul><li>Seismograms from three different locations are needed to locate the epicenter. </li></ul><ul><ul><li>The difference in arrival times of the P and S waves are used to calculate it. </li></ul></ul>
  13. Continued – See page 55 All waves, including seismic waves, carry energy from place to place.
  14. Continued – See page 56 Seismographs record ground movement.
  15. Continued – See page 57 Scientists use seismograph information to locate the epicenter of an earthquake.
  16. Section 2.3 Earthquake Damage Can Be Reduced
  17. Earthquakes can cause severe damage and loss of life. <ul><li>The Moment Magnitude Scale, and The Richter Scale, are used to measure magnitude. </li></ul><ul><li>Loss of life, structural damage, fires, landslides, and sinking of structures due to liquefaction (soil acting like a liquid) can be devastating. </li></ul><ul><li>Aftershocks, weaker earthquakes, often follow. </li></ul><ul><li>Earthquakes can trigger tsunamis which travel quickly as a series of waves. </li></ul>
  18. Continued – See page 51
  19. Some scientists work to monitor and predict earthquakes. <ul><li>Predictors include: </li></ul><ul><ul><li>Changes in elevation of the ground. </li></ul></ul><ul><ul><li>Slow movement of blocks of rock. </li></ul></ul><ul><ul><li>Formation of small cracks in the ground. </li></ul></ul><ul><li>Seismic Gap: area along an active fault where no quakes have occurred for a long time. </li></ul><ul><ul><li>May indicate stress is building up. </li></ul></ul>
  20. Continued – See page 64 Scientists cannot yet predict the day or even year when an earthquake will occur, but they can make long term predictions.
  21. Continued – See page 65
  22. Structures can be designed to resist earthquake damage. <ul><li>Strict building codes are enforced in active earthquake regions. </li></ul><ul><ul><li>Steel reinforced shear walls </li></ul></ul><ul><ul><li>Fastened to foundation </li></ul></ul><ul><ul><li>Isolators between the building and foundation. </li></ul></ul><ul><ul><li>Cross braces </li></ul></ul>

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