Earthquakes

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  • Earthquakes
    • Natural hazard -  A naturally occurring event that has the potential to affect people's lives or property
    • The centre of the earth is the core. Inner - ball of solid iron and nickel. Outer - liquid. Around it is the mantle, which is semi-molten rock.
    • Plates
      • The plates move because the rock in the mantle underneath is moving.
      • Plate boundaries or margins are the places where plates meet.
      • The outer layer  is the crust. Very thin - 20km. It's divided into lots of slabs called tectonic plates. Their made of continental and oceanic crust.
        • Oceanic - thinner and more dense
        • Continental - Thinker and less dense.
    • Margins
      • Destructive -  Two plates move towards eachother. The oceanic plate (denser) is forced down and destroyed. Often creates volcanoes.
        • Pressure builds when one plate gets stuck as it's moving down past the other into the mantle.
          • They eventually jerk past each other, sending out shock waves. These vibrations are the earthquake.
            • Pressure builds along cracks within the plates as they move away from each other.
            • Pressure builds up when plates that are grinding past each other get stuck.
      • Constructive - Two plates are moving away from each other. Magma rises to fill the gap and new land is formed.
        • Pressure builds along cracks within the plates as they move away from each other.
      • Conservative - Two plates are sliding past each other, or are moving in the same direction at different speeds.
        • Pressure builds up when plates that are grinding past each other get stuck.
    • Focus - The point in the Earth where the earthquake starts.
    • Epicentre - The point on the Earth's surface, directly above the focus.
  • Natural hazard -  A naturally occurring event that has the potential to affect people's lives or property
  • The outer layer  is the crust. Very thin - 20km. It's divided into lots of slabs called tectonic plates. Their made of continental and oceanic crust.
    • Oceanic - thinner and more dense
    • Continental - Thinker and less dense.

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