Tectonic hazards

• Types of natural hazards

  • Geological- forms from the land
  • Atmospheric- forms from the atmosphere
• A natural hazard only becomes a disaster if people are affected/people die/emergency aid is required
• Types of plate boundaries

  • collision
  • destructive
  • Constructive
  • Conservative
• Plume


  Magma that rises to the surface
• Convection currents

  1. Magma rises in the mantle to the surface

  2. Cools and sinks back to the base of the mantle

  3. Reheated and rises once more
• The majority of earthquakes and volcanoes are found along narrow, global bands know as the plate margins or plate boundaries
• Convection currents move the plates


  Depending on the direction of magma movement under the surface of the crust
• All plate boundaries occur due to convection currents
• Structure of the earth

  • Crust - two types: oceanic and continental
  • mantle
  • outer core
  • inner core

  
• Destructive plate boundary: two plates move towards each other. Thinner and denser oceanic plate subducts beneath the thicker and less dense continental plate. Friction occurs resulting in an earthquake. Oceanic plate melts in the mantle, mixing with the sub ducted sea water. making the magma a different density to the mantle, rising upwards and erupts as a volcano.
• Constructive plate boundary: two plates move away from each other creating a gap. Also there’s a result in an earthquake due to the friction of plate moving across the mantle. Magma rises to fill the gap creating a volcano
• Conservative plate boundary: two plates slide past each other until stopped by the outcrops of rock, creating friction as they are still trying to move but physically can’t. There’s a build up in pressure, large amounts of friction result to the earthquake.
• Collision plate boundary: two continental plates move towards each other. They have the same density so one can’t subduct the other. They buckle up and form fold mountains. The pressure and movement of rock crumbling upwards can cause friction and earthquakes.
• Why live near a volcano?

  • Volcanic ash creates fertile soil. Encouraging crop growth meaning that farmers crop yield increases so that they have more crops to sell therefore can make more money
  • Many tourists visit volcanoes. Meaning local shop owners can make a lot of profit selling goods to the tourists. The more money they earn, the better QoL becomes as they can afford to do nice things like going on holiday
  • Volcanoes are home to many precious minerals. This provides job opportunities and also improves the wealth of the country
• Why live near an earthquake?

  • Earthquake plate margins are often associated with a source of water and so provides a good location for many homes
  • Plate margins also provide the opportunity for geothermal energy which is a renewable energy source, providing the country with cheap electricity and a powerful energy source to sell
• How can we reduce risks from tectonic hazards?

  We can monitor both volcanoes and earthquakes, however, this is often inaccurate. In addition it also hard to predict when an earthquake or volcano will occur as there are not many warning signs. Therefore planning and protection are the best strategies.
• One way to reduce risk from tectonic hazard: Planning

  including

  • where to meet your family after the disaster
  • having an earthquake kit with food and water
  • evacuation plan in school
  • drop cover and hold practice
• Protection

  Reducing the risks from tectonic hazards
• Roof of house

  • Not flat to prevent the weight of ash from causing it to cave in
• Earthquake protection

  • Cross bracing to reduce the sway of a building
  • Counterweights on top of the building to reduce swaying motion
• Deep foundation

  • Covered by shock absorbers to absorb as much of the earthquake's energy as possible and reduce the impact on the actual building
• Gas shut off valves

  • Inside the building to stop the spread of fires
• Automatic shutters

  • Help to stop breaking glass falling on people and creating further injury