Hazards

• Hazards


  • Geophysical (caused by land)
  • Atmospheric (caused by climate)
  • Hydrological (caused by water)
• Disaster


  When a hazard seriously affects humans
• Hazard risk


  Likelihood that people will be affected
• Vulnerability


  How susceptible a population is to a particular hazard
• Hazard perception


  People's circumstances affecting their perception of hazards
• Human responses to hazards

  • Fatalism (accept it and get on with it)
  • Prediction (work out when and where it will occur)
  • Adaptation (change how you live)
  • Mitigation (reduce the impact)
  • Risk sharing (e.g. insurance)
• Incidents (how often it will happen) and level of development affect human responses to hazards
• Plate tectonics


  Theory that the lithosphere is divided into plates that move
• Evidence for plate tectonics

  • Continental drift (fossil remains, rock types, continent shapes)
  • Paleomagnetism
• Plate movement processes


  • Convection currents
  • Slab pull
  • Ridge push
• Layers of the Earth


  • Inner core
  • Outer core
  • Mantle
  • Crust (continental and oceanic)
• Constructive/Divergent plate margin


  Plates move apart, magma upwells, forms ocean ridges, rift valleys, volcanoes, earthquakes
• Destructive/Convergent plate margin


  One plate subducts under another, forms fold mountains, deep sea trenches, volcanoes, earthquakes
• Oceanic-Oceanic convergence


  Forms island arcs, deep sea trenches, volcanoes, earthquakes
• Continental-Continental convergence


  Forms fold mountains, earthquakes
• Conservative plate margin


  Plates move past each other, no subduction, only earthquakes
• Hotspots/Magma plumes


  Magma rises through plate, forms volcanoes not at plate margins
• Park model


  Describes stages of disaster response: pre-disaster, disruption, relief, rehabilitation, reconstruction
• The Park model assumes human factors don't affect events, and that LICs/NEEs may not be able to afford improvements
• The hazard management cycle is less suited to unexpected hazards and progress is less visible than the Park model
• Primary volcanic hazards


  • Pyroclastic flows
  • Superheated gas
  • Ash fallout
• Secondary volcanic hazards


  • Acid rain
  • Lahars
• Factors affecting volcanic hazards

  • Magnitude
  • Frequency
  • Randomness
  • Predictability
• Impacts of volcanic hazards

  • Economic
  • Political
  • Social
  • Environmental
• Responses to volcanic hazards

  • Short-term
  • Long-term
• Mount Pinatubo eruption


  • Largest eruption in 50 years
  • Over 600 years since last eruption
  • 350 deaths
  • 80,000 hectares of farmland buried
  • 94% of deaths in evacuation camps
• The responses to Mount Pinatubo were lacking in long-term management and preparation, despite evidence of past violent eruptions
• Earthquakes


  Caused by the build-up and sudden release of strain energy as plates jerk past each other
• Epicenter


  The point on the Earth's surface directly above the focus (origin) of an earthquake
• The nature of earthquakes is affected by the type of plate margin, rate of plate movement, and depth of the focus
• The local people that are left vulnerable use the geological evidence we're aware that volcano erupted violently in the past but still no preparation had been made so you could argue actually here they've been let down by the planning and the responses previously
• Strain energy


  Tension that builds up in plates that are going to jerk past each other, causing shock waves to spread out from the focus
• Epicenter


  The point on the earth's surface directly above the focus of an earthquake
• Factors affecting the nature of earthquakes

  • Type of margin
  • Rate of movement
  • Depth of the focus
• If worst came to worst you'd start thinking generically about exactly what could the impact of an earthquake be if it happened right now
• Secondary seismic hazards


  • Tsunami
  • Other secondary impacts
• Richter scale


  Measures the magnitude of an earthquake, a logarithmic scale
• Cali scale


  Measures earthquakes using observations
• Earthquake responses


  • Preparedness
  • Adaptation
  • Prevention
• Socially, Kobe has lost a lot of traditional buildings but gained new earthquake resistant homes and suburban areas