Tectonic hazards

• Conservative plate margin


  1. Two plates move past each other

  2. Creates friction

  3. Once pressure has been released, an earthquake can occur
• Constructive plate margin


  1. Two plates move away from each other

  2. Magma rises to fill the gap

  3. New crust is formed

  4. Volcanoes can sometimes form and earthquakes can also occur
• Destructive plate margin - fold mountain

  1. Two plates move towards each other (with the same density creating a fold mountain)

  2. Forms volcanoes and earthquakes
• Destructive plate margin - subduction


  One plate gets subducted under another plate and melts, forming magma (different densities)
• Monitoring natural hazards


  • Earthquakes occur without warning so can't easily be monitored
  • Earthquakes could be monitored via laser beams, a seismometer and levels of radon gas
  • Volcanoes can be monitored via remote sensing, ground deformation and gas
• Prediction of volcanic eruption


  Based on scientific monitoring
• Scientists are unable to make accurate predictions of earthquakes
• How to predict a volcano

  • A small dent or bulge in the side
  • Measure the gases being released
  • Snow melting from the top (could cause a flood)
  • Local water supply contaminated
• Protection from natural hazards

  • Make earth embankments to divert lava flow
  • Construct buildings and bridges to resist ground shaking
• Primary effects


  Caused by the ground shaking, can include damage to infrastructure (structures falling, people dying, water cut off)
• Secondary effects


  The result of primary effects, can include tsunamis, fires and landslides, homelessness, blocked roads, lack of medical help
• Immediate responses to natural hazards


  • Search and rescue
  • Providing medical care, food, water and shelter for survivors
• Long-term responses to natural hazards

  • Rebuilding and construction
  • Returning peoples lives back to normal
  • Reducing future risk (foreign aid, power supplies)
• Continental drift


  The movement of the continents over geological time
• Alfred Wegner published the theory of continental drift

  1912
• There used to be a supercontinent called Pangea and over time the continents broke apart
• Convection currents


  One of the causes of continental drift
• Evidence of continental drift

  • The same types of fossils, plants and animals found in South America and Africa
  • The east coast of South America fits perfectly into the west coast of Africa
  • Rock formations and mountains match in South America and Africa
  • Similar mineral deposits and natural resources, including coal, exist in west coast of Africa and east coast of South America
• Earthquakes


  1. Plates become unstuck and eventually slide past each other

  2. This sends out shock waves from the focus - this is the earthquake

  3. Near the focus, the waves are stronger and cause more damage
• Epicenter


  The point on the ground directly above the focus
• Focus


  Where the earthquake begins
• Fault


  A weak point in the tectonic plate where pressure within the crust is released
• Earthquakes are measured on the Richter scale
• Reasons why people live near tectonic hazards

  • Earthquakes and volcanic eruptions don't happen often, they are not seen as a threat
  • Better building designs can withstand earthquakes
  • People living in poverty may focus on other issues like money, food, security and family
  • Plate margins often coincide with attractive areas to live
  • People may not be aware of the risks
  • Volcanoes can bring benefits: fertile soil, rocks for building, rich mineral deposits, hot water, fault lines of earthquakes allows water supplies to reach the surface
• Effective monitoring of volcanoes and tsunamis enables people to receive warnings and evacuate before it happens
• Global distribution of earthquakes and volcanic eruptions

  • Earthquakes form on/around plate margins, most located in the Pacific Ocean, the least in Europe and Africa
  • Volcanoes form on/around plate margins, found on destructive and constructive margins, lots around the Pacific Ocean, especially the Philippines and South Asia, also west and south of North America
• Richter scale


  A scale used to measure the magnitude of earthquakes