Tectonics knowledge

• Crust


  The thin and solid outermost layer of the Earth above the mantle
• Two types of crust


  continental and oceanic
• Lithosphere

  Crust and solid portion of mantle
• Aesthenosphere

  Part of mantle beneath crust
• Mantle

  Thickest layer, made up of hot rock
• Outer core


  the liquid layer of the Earth's core that lies beneath the mantle and surrounds the inner core
• Inner core


  A dense sphere of solid iron and nickel at the center of Earth
• Ridge push


  Magma escapes through crust forces plates apart
• Slab pull


  Cooler magma sink back to mantle. Drags oceanic crust into mantle
• Convergent Boundary (Continental)


  Two plates move TOWARDS each other
• Divergent boundary

  Two plate move AWAY from each other
• Conservative boundary

  Two tectonic plates slide past each other
• Earthquakes


  Friction between plates, causes sudden movements to occur as pressure builds, sending vibrations across the land.
• Hot spots


  Places where molten material from the mantle reaches the lithosphere
• Hawaii

  Plate drifts across the hot spot, chain of volcanic islands form
• Physical hazard profile


  Magnitude, predictability, frequency, duration., speed of onset and areal extent
• Measure of earthquake mag

  Richter scale
• Shield volcanoes


  Converging boundaries, basaltic magma erupts forming shield volcanoes
• Pyroclastic flow


  Clouds of superheated rock and ash, travel at speeds of up to 700km per hour
• Lava flows

  Burns anything in it's path. Solidifies leaving layer of new rock
• Ash fall


  No immediate deaths, long term problems

  - Respiratory problems due to fine ash in the air

  - Landscapes covered= loss of food crops

  - Poor visibility

  - Closure of airports
• Toxic gases


  CO2 and hydrogen sulphide are released. People can suffocate.
• Eyjafjallajokull (volcano), Iceland


  Lava flows, ash cloud, VEI4. airports close,
• Environmental impacts of tectonic processes

  - Destruction of forests

  - Flooding

  - Areas burned by lava flow

  - Cooler temps, ash block sun
• Economic impacts of tectonic processes

  - Damage to farmland and crops

  - Roads, rail, airports inaccessible or unusable

  - Loss of business
• Social impacts of tectonic processes


  - injuries or health issues

  - Homelessness

  - Loss of service such as schools or hospitals
• Mount Merapi, Indonesia


  2010, VEI 4, 200,000 people homeless, 320,000 displaced. Poor sanitation, no privacy, disease risk in evacuation centres. Lava flows, closed roads. 353 people killed, 500 killed due to earthquake that followed.
• Liquefaction


  Soil is shaken violently during earthquake, makes it behave as a fluid.
• Landslides


  Material on a slope is unstable.
• Ground shaking


  - Vibrations radiate outward from focus of an earthquake in P and S waves

  - Amplitude of ground shaking decrease with distance from epicentre
• Effects of ground shaking

  - Destruction or damage to buildings and transport networks

  - Rupture of water/mains/ gas pipes/ electricity lines

  - Fires ignite due to the above

  - Deaths and injuries from falling debris

  - Flooding
• Primary environmental impacts of earthquakes

  - Destruction of forests made coastal ecosystems

  - Drowning animals
• Secondary environmental impacts of earthquakes

  - Fires

  - Pollution as toxic waste or substances may be release into the environment air and water
• Primary economic impacts of earthquakes

  - Destruction of industry

  - Destruction of buildings

  - Destruction of transport networks
• Secondary economic impacts of earthquakes

  - Destruction of settlements by tsunami

  - Fiires
• Primary social impacts of earthquakes

  - Injuries

  - Homelessness

  - Rupture of gas and water mains and damage to power lines

  - Destruction of public services such as school and hospitals
• Secondary social impacts of earthquakes

  - Fires

  - Pollution as toxic waste or substances may be released into the environment

  - Disease as sewage mixes with water supplies
• Nepal, 2015


  9,000 killed

  600,000 structures and towns nearby damaged

  Lots of aftershocks

  Landslides produced

  Damage cost $5- 10billion
• New Zealand, Christchurch 2011


  185 killed

  Struck lunchtime= lots of people on streets

  Liquefaction- damage properties
• Factors that lead to high vulnerability

  Root causes- Unstable gov, poverty

  Dynamic pressure- Large population, low levels of tech, poor health care/education

  Unsafe conditions- poor quality housing, fragile local economies, located at plate margin.