Geo natural hazards

• Core


  The centre of the Earth
• Mantle


  A layer of molten rock surrounding the core
• Crust


  The thin layer on the surface of the Earth
• Oceanic crust


  • Denser and thinner (5km thick)
• Continental crust


  • Less dense, but thicker (30 km)
• Tectonic plates


  The large pieces that make up the Earth's crust
• Tectonic plate movement


  1. Plates may move apart

  2. Plates may move closer together

  3. Plates may slide past each other
• Tectonic plate movement


  Leads to formation of fold mountains and volcanoes
• The crust is unstable because the plates may move
• Iceland sits on the boundary of two tectonic plates
• Tectonic plate movement


  1. Heat from Earth's core creates convection currents in the mantle

  2. Hot molten rock rises

  3. Moves the plates on the surface which form the crust
• A destructive plate margin is when plates move together
• A constructive plate margin is when plates move apart
• A conservative plate margin is when plates slide past each other
• Destructive plate margin


  • Subduction of the South American Plate under the Nazca Plate
• Constructive plate margin


  • Mid-Atlantic Ridge between the North American and Eurasian Plates
• Conservative plate margin


  • San Andreas Fault between the Pacific Plate and North American Plate
• Destructive plate margin


  • Lighter continental crust is pushed down into the mantle
  • Denser oceanic crust stays on top and melts
• Destructive plate margin


  • Rising magma can cause composite volcanoes
  • Energy builds in the subduction zone and is released as earthquakes
  • Fold mountains are formed
  • Ocean trenches are formed
• Constructive plate margin


  • Usually found under the sea
  • Ridges and shield volcanoes are formed by the build up of magma
  • Volcanoes can form islands if they rise above sea level
• Conservative plate margin


  • Earthquakes occur when built up pressure forces plates unstuck
• Iceland is located on a constructive plate margin
• Conservative plate margin


  • San Andreas Fault
• Plate movement


  Triggers earthquakes