Hazards and Plate Margins, what Happens?

• Hazard Risk


  The chance that a place will be affected by a natural event
• Natural hazards pose major risks to people and property
• Factors affecting hazard risk

  • Magnitude of the hazard
  • Frequency
  • Population density
  • Level of development
• Magnitude


  The size of the hazard event
• If there is a large magnitude hazard event


  Hazard risk increases
• Frequency


  How often the hazard occurs
• If a hazard occurs frequently

  Hazard risk decreases
• Population density


  The number of people in an area and how close together they are
• The greater the number of people in an area


  The greater the potential for disaster
• Level of development


  How much money is available to prepare for and respond to the event
• Country development levels


  • Low Income Countries (LIC)
  • Newly Emerging Economies (NEE)
  • High-Income Countries (HIC)
• Layers of the Earth


  • Inner Core
  • Outer Core
  • Mantle (Mesosphere, asthenosphere and lithosphere)
  • Crust
• Continental Crust


  Can be up to 3.8 billion years old
• Oceanic Crust


  Usually less than 200 million years old
• Tectonic Plates


  Large fragments of the lithospheric crust
• Plate Boundary


  Where two tectonic plates meet
• Types of plate boundaries

  • Constructive- where plates move apart
  • Destructive- where plates move together
  • Conservative- where plates slide past each other
• Tectonic plates are constantly moving at a few centimetres each year
• How tectonic plates move

  1. Slab pull

  2. Ridge push
• Volcanoes and earthquakes occur at constructive plate margins
• How volcanoes and earthquakes occur at constructive plate margins

  1. Magma rises to the surface

  2. Creates a ridge

  3. Rock cools and slides down ridge, pushing plates apart

  4. Magma erupts through crust, creating undersea volcanoes
• Iceland experiences earthquakes besides volcanic eruptions
• Rift Valley


  Steep-sided valleys that form at constructive plate margins as the plates move apart
• Landforms found at constructive plate boundaries

  • Shield Volcanoes
  • Ocean Ridges
  • Rift Valleys
• Thingvellir National Park in Iceland is popular with tourists
• Destructive Subduction


  Denser oceanic plate is forced underneath the lighter continental plate down into the mantle
• Destructive Collision


  When two continental plates meet, they are forced upwards to form mountain ranges
• Destructive Subduction (oceanic and oceanic)


  Colder, denser, older oceanic plate is forced below the other into the mantle, forming an oceanic volcanic island arc
• What Destructive Margins form

  • Composite Volcanoes
  • Fold Mountains
  • Deep Ocean Trenches
• The Mariana Trench is the deepest known part of the Earth's oceans, at 10,994 metres deep
• Conservative Plate Boundaries


  Plates slide past each other, can be moving in the same or different directions, at the same or different speeds
• Volcanoes don't form at conservative plate boundaries
• Following an earthquake along a conservative plate boundary


  There are often aftershocks as the additional stress on other areas along the fault are relieved