Tectonic Hazards

• Natural hazard

  A natural process which could cause death, injury or disruption to humans, property and possessions
• Why plates move

  1. Radioactive decay in core generates heat

  2. Lower mantle rock heats up, becomes less dense and rises

  3. Rock cools, becomes more dense and sinks

  4. Convection currents created

  5. Convection currents cause drag on tectonic plates, making them move
• Convection currents


  Circular movements of semi-molten rock in the mantle
• What causes an earthquake

  1. Plates become locked, causing friction and pressure buildup

  2. Pressure is eventually released, triggering plates to move

  3. Movement causes seismic waves to travel from the focus to the epicentre

  4. Crust vibrates, triggering an earthquake
• Epicentre


  Point directly above the focus where seismic waves reach first
• Seismic waves


  Energy waves that travel out from the focus
• Focus

  Point at which pressure is released
• Structure of the Earth

  • Crust (5-10km thick, made of plates)
  • Mantle (2900km thick, semi-molten rock in convection)
  • Inner and Outer Core (5000 degrees, mostly iron and nickel, inner solid, outer liquid)
• Constructive plate boundary

  • Plates move apart, new magma reaches surface, forms submarine mountain range
• Destructive plate boundary

  • Denser plate subducts under other, friction causes melting and magma formation, volcanoes and earthquakes
• Conservative plate boundary

  • Plates slide past each other, causes earthquakes (e.g. San Andreas Fault)
• LIC

  Low Income Country
• Monitoring earthquakes

  • Very difficult
  • Foreshocks using seismometers could indicate a big earthquake
• Predicting earthquakes

  • Extremely difficult to predict time, date or exact location
• Protecting against earthquakes

  1. Sea wall in case of tsunami

  2. Building and transport design improvements (deep foundation, shock absorbers, plastic glass, clear evacuation routes)

  3. Strict building regulation
• Planning for earthquakes

  1. Practice drills

  2. Preparing emergency supplies and location of evacuation centre

  3. Securing objects and furniture