Geography

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Anonymous
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25757
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Geography
Updated:
2010-07-05 21:28:26
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Geography plate tectonics
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Geography
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  1. Crust
    thin, solid rock of the earth's surface. Covered by oceans and part forms the land. It is about 5-55 km thick.
  2. Mantle
    Below the crust. About 3000 km thick. Consists very hot semi-molten rocks (1600C) The lava of volcanoes comes from and goes through cracks in the Crust
  3. Inner and Outer Core
    Interior parts of the Earth. Very hot temperatures (2000C) Made out of NIFE (nickel+iron rocks) Very dense. Total radius is about 3500 km from the Earth's center
  4. Density
    helps the crust of Earth float because the crust is less dense than the mantle.
  5. The crust moves around because
    Convection Currents
  6. The continental plate
    less dense then the oceanic place
  7. Why does the crust move?
    Convection currents exist in the mantle. Heat flows from hotspots to cooler areas. The source of the heat driving the convection current is radioactive decay which is happening deep in the Earth.
  8. What are the plates
    crust breaks up into large segments
  9. Continental crust
    less dense rock (thickest crust up to 80km)
  10. Oceanic Crust
    denser rock (thinner crust 10-12km)
  11. Types of plate boundaries
    • Constructive (Diverging/Splitting)
    • Destructive (Converging/Collision)
    • Conservative (Transform-Fault/Sliding)
  12. Subduction Zone
    When continental crust collides with oceanic crust
  13. Continental Collision
    When two continental plates collide.
  14. Friction
    causes plates to get stuck
  15. Pangea
    large super continent that scientists believe existed on Earth around 400 million years ago.
  16. What is some evidence that the continents were once joined?
    The shape of the continents fit together like a jigsaw

    Same rock types and identical plant and animal fossils of the same age have been found in rocks in Africa and South America

    • Distribution of animals proves that places have separated.
    • Example : Africa - Cheetah, South America - Jaguar

    Types of rocks found on each continent today show similar strata and ages. Mountain range on the coast of West Africa disappear then suddenly reappear again on the coast of South America.
  17. How do we record earthquakes?
    • Richter Scale
    • Mercalli Scale
  18. Richter Scale
    The strength or magnitude of an earthquake is measured by this. Measurements are logarithmic, this means that each whole number step represents a ten-fold increase in measure amplitude. This means a magnitude 7 earthquake is 10 times larger than a 6 and 100 times larger than a magnitude 5.
  19. Amplitude
    (Size of wave) enables us to record the amount of energy
  20. Seismometer
    recording device that measures earthquakes
  21. Mercalli Scale
    Observational scale, assesing the damage cause from I to XII
  22. Why are some earthquakes more damaging in some places than others?
    • Socio-Economic Factors - Population Density, Wealth of the area, Education of Population, Preparation
    • Physical Factors -Type of soil may mean liquefaction occurs, Proximity to coast, tsunami risk, Danger of landslide
  23. Mitigation of Earthquakes
    • Prediction
    • Preparation
  24. PREDICTION - What are some possible indicators of an earthquake?
    • Animal behavior
    • Water levels in wells drop or rise
    • Build up of electro-magnetic radiation can be monitored
  25. Gap Theory
    States that along faults that are seismically active, the regions that are more likely to experience earthquakes in the near future are those that have not shown seismic activity in some time.
  26. PREPARATION - Civil Defense Organization
    • emergency supplies
    • food
    • water
    • portable toilets
  27. Preparation
    • Building Regulations
    • Education
    • Rescue Teams
    • Civil Defense Organization
  28. PREPARATION - Building regulation suggestions
    Buildings need to be made of reinforced concrete.

    A height limit should be placed on buildings in places that have sandy soils.

    Land use zoning: Make it ilegal to build in areas that are unsafe.
  29. PREPARATION - Education
    Drills carried out by an institution

    Simulations carried out by a whole area
  30. PREPARATION - Rescue Teams
    Ready for emergencies best provided in EMDCs
  31. Name the times of periods that existed millions of years ago.
    • Permian-225 million years ago
    • Triassic - 200 million years ago
    • Jurassic - 135 million years ago
    • Cretaceous - 65 million years ago
  32. Earthquakes
    Occur along plate margins (where plates meet). Happens when plates move past, towards or away from each other the movement is not smooth. Occurs when the build up of pressure (plates that get stuck and the pressure builds up) is released.
  33. Focus
    The point where the earthquake starts
  34. Epicenter
    The point at ground level directly above the focus
  35. How does a seismometer work
    The whole seismometer moves as the earth is attached to shakes but the heavy mass does not move because of its inertia. The recording device measures how far the rest of the seismometer has moved with respect to the mass.
  36. How is the Mercalli Scale measured?
  37. What are the two types effects of an earthquake?
    • Direct - effects that are caused by the earthquake
    • Indirect - Events set of as a consequence of the earthquake (there is a time delay)
  38. What are Direct Effects of an earthquake?
    • Building collapses
    • Subsidence
    • Liquefaction
  39. Subsidence
    downwards motion of earth's surface
  40. Liquefaction
    when ground behaves like liquid and so loses its ability to carry weight
  41. What are Indirect Effects of an earthquake?
    • Fires
    • Tsunamis
    • Landslides
    • Epidemics
  42. In which boundaries do earthquakes happen?
    • Constructive
    • Subduction Zone
    • Continental Collision
    • Consevative
  43. In which boundaries do volcanoes happen?
    • Constructive
    • Subduction Zone
  44. In which boundaries do Fold Mountains happen?
    • Subduction Zone
    • Continental Collision
  45. In which boundaries do Ocean Trenches happen?
    Subduction Zone
  46. In which boundaries do Mid-Oceanic Ridges happen?
    Constructive

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