Natural + Tectonic Hazards

• A natural hazard is an environmental phenomenon which have the potential to affect human society

  examples are:

  • Droughts
  • Avalanches
  • Floods
• Constructive plate margins have slab pull which causes the plates to move in opposite directions, creating new land for magma to push out. This slab pull is created by the theory of convection currents rising and condensing. An example of this is the East African Rift Valley
• The destructive margin has the oceanic crust moving towards a continental crust, dragging down into the subduction zone as it gets older and denser. This causes magma to rise from the partially melted crust.
• The conservative margin has two plates moving either at the same direction at different speeds or in different directions. This causes stress between the plates, causing earthquakes from the build up of pressure. An example of this is the San Andreas Fault on the North American and Pacific plate margins
• The collision margin has crusts which are folded upon each other, creating huge mountains like the Himalayas where Mount Everest is. The most upper layer is the continental crust, then the lithosphere, then the mantle. This happens because neither plate is more or less dense than the other so they simply crash together, creating force upwards
• Reasons for living in areas at risk of earthquakes:

  • Infrequent earthquakes
  • Good planning and protection
  • Good government resources to cope
  • Tourism
• Reasons for living in areas at risk of volcanoes:

  • Fertile soil
  • Geothermal energy
  • Valuable material
  • Tourism
• A tectonic hazard is a hazard created when the earth's crust moves
• Geomorphic hazards are hazards orgininating on or near the earth's surface e.g: landslides, flooding and mudflows
• Biological hazards are of organic origin or conveyed by biological vectors e.g: pathogenic microorganisms, toxins
• Atmospheric hazards are hazards to humans created in the atmosphere e.g: tropical storms, droughts, tornadoes
• The crust is the topmost outer layer of the earth
• Oceanic crust is the surface of the Earth's crust found underneath the oceans, forming the ocean floor
• The continental crust is the layer of granitic, sedimentary, and metamorphic rocks, which form the continents and the areas of shallow seabed close to their shores
• The core is the hot centre of the Earth
• Mantle is a layer within the Earth between the crust and core
• Ridge push is one of the main driving forces of plate tectonics. It refers to the pushing force that plates experience as they slide down the raised asthenosphere underneath Mid Ocean Ridges.
• Slab pull is a force that results from denser oceanic plates sinking beneath less dense continental plates along convergent boundaries and subduction zones. The gravitation force of the sinking oceanic plate drags the rest of the oceanic plate along with the portion experiencing slab pull.
• Convection currents describe the rising, spread, and sinking of gas, liquid, or molten material caused by the application of heat.
• A rift valley can simply be characterized as a flat, low-lying valley that forms at a geographical crack or separation. Rift valleys form when tectonics plates beneath the Earth's surface diverge (or move away from one another in opposite directions).