Tectonic

• Convection currents

  
• Types of plate movement:

  • Destructive - slab pull
  • Consructive - ridge push
  • Conservative - plates move against each other ↑↓
• Global distribution of earthquakes and volcanoes:

  • Are where two plates meet, called plate margins
  • Often are found together
• Continental plate:

  • Land
  • Thick
  • Less dense
• Oceanic plate:

  • Ocean
  • Thin
  • More dense
• 'Ring of Fire' is where there is a lot of volcanic activity and earthquakes around the edge of the pacific ocean

  
• Convection currents:

  • Inner core heats up the mantle and magma
  • As this heats up it becomes less dense, so it starts to rise
  • As it reaches the crust it starts to cool, making it more dense and therefore sink
  • This repeats in a circular motions
• Ridge push & Slab pull:

  • Magma rises up and pushes the oceanic crust away (ridge push)
  • Then the oceanic crust is subducted under, as it is more dense than continental crust (slab pull)
• Constructive plate margins:

  1. Convection currents and ridge push
  2. This causes the plates to pull apart
  3. When plates are being pulled, there will be friction, which will cause earthquakes
  4. Then magma rises to the surface
  5. When magma reaches the surface a volcano forms
• Destructive plate margins:

  1. Convection currents, ridge push and slab pull
  2. Plates move towards each other
  3. During this friction can cause earthquakes
  4. The oceanic plate is subducted and melted, as it is more dense than continental plate
  5. Magma rises to the surface
  6. Causing volcanoes to erupt

  
• Conservative plate margins:

  1. Convection currents
  2. Plates move in opposite directions
  3. Friction can cause the plates to jam, this causes earthquakes

  
• How to reduce effects of tectonic hazards:

  • Monitoring
  • Prediction
  • Protection
  • Planning
• Monitoring:

  ~Earthquakes~

  - Seismometers are used to measure foreshocks before the earthquake

  - Groundwater levels change before an earthquake, the water can escape from the ground prior it

  - Animals behave strangely when an earthquake is meant to happen

  ~Volcano~

  - Satellite monitor ground deformation and heat changes

  - Seismometers measure small earthquakes

  - Gas trapping bottles measure radon gases released
• Prediction:

  ~Earthquake~

  - It's impossible to make clear predictions because they don't have clear warning signs

  - Scientists study historical data, which tells them which area is at greatest risk

  ~Volcano~

  - Prediction is based on monitoring
• Protection:

  ~Earthquakes~

  Buildings can be designed to withstand earthquakes;

  - Birdcage structure with interlocking steel frame

  - Fire resistant material

  - Shock absorbers

  - Rolling weights on roofs to counteract shock waves

  - Automatic shutters, preventing glass from falling

  - Open areas for evacuation and emergency access

  ~Volcano~

  - People can use explosives and earth walls to divert lava
• Planning:

  • Hazard mapping - used to show which areas are likely to be worst effected or most at risk
  • Education - teaching and educating the public through school, TV and radio
  • Evacuation - restricting areas at risk and evacuating when an eruption occurs (only for volcanoes)