Natural Hazards

• Natural Hazard


  A threat to people or property
• Natural Disaster


  A natural hazard that has actually happened
• Extreme events which do not pose any threat to human activity are not counted as hazards (eg drought in an uninhabited desert or an avalanche in Antarctica)
• Two Main Types of Natural Hazard

  • Geological Hazards
  • Meteorological Hazards
• Geological Hazards


  • Caused by land and tectonic processes
  • Examples: volcanoes, earthquakes, landslides, avalanches
• Meteorological Hazards


  • Caused by weather and climate
  • Examples: tropical storms, extreme weather, heatwaves, cold spells, climate change
• Factors Affecting Hazard Risk

  • Vulnerability
  • Nature of Natural Hazards
  • Capacity to Cope
• Vulnerability


  The more people in areas exposed to natural hazards, the greater the probability they will be affected, so the hazard risk is higher
• Vulnerable Areas


  • High population density on a flood plain (like Bangladesh)
  • City at the base of a volcano (like Naples, Italy)
• Capacity to Cope


  The better a population can cope with an extreme event, the lower the threat
• Coping Capacity


  • Developed countries can afford to build flood defences, evacuate people, and repair damage
  • Developing countries have less capacity to cope
• Nature of Natural Hazards

  • Some hazards can be predicted and monitored (e.g. tropical storms), giving time to evacuate
  • Some happen suddenly with no warning (e.g. earthquakes), making it harder to protect people
• Frequency


  • Some natural hazards occur more often than others, increasing the hazard risk
• Magnitude


  • More severe natural hazards cause greater effects than less severe natural hazards
• Magnitude of Earthquakes


  • 2011 Japan earthquake (magnitude 9.0) killed over 15,000 people
  • 2009 L'Aquila, Italy earthquake (magnitude 6.3) killed around 300 people
• Adaptation


  Responding to climate change by coming up with ways to live and cope with the effects
• Atmospheric circulation


  The general movements of air around the Earth due to pressure and temperature
• Atmospheric hazard


  Hazards caused by the weather and processes in the atmosphere
• Carbon Capture and Storage (CCS)


  The process of capturing carbon dioxide that would normally be emitted into the atmosphere and storing it underground in reservoirs
• Climate change


  A distinct change in global or regional patterns of climate, such as changes in temperature or precipitation patterns
• Conservative plate margin


  A plate margin where two plates are moving alongside each other
• Constructive plate margin


  A plate margin where two plates are moving away from each other
• Continental crust


  The thicker, less dense crust that makes up the continents
• Convection current


  The movement of a fluid caused by a difference in temperature or density
• Coriolis Effect


  The effect of the Earth's rotation on wind movements
• Cyclone


  A tropical storm that hits Oceania or Madagascar
• Destructive plate margin


  A plate margin where two plates are moving towards each other
• Eccentricity


  The changing of the orbit of the Earth around the Sun from a circular shape to an ellipse
• Eye


  An area of a tropical storm with extremely low pressure and calm conditions
• Eyewall


  An area of a tropical storm with the most intense, powerful winds and torrential rain
• Ferrel Cell


  At around 60° either side of the equator, moist air rises, and travels to lower latitudes at around 30° where it sinks, along with air travelling from the equator
• Fossil fuels


  Fuels made up of the remains of organic material, such as oil, coal and gas
• Geological hazard


  A hazard caused by processes on the land
• Greenhouse Gases


  Gases in the Earth's atmosphere that trap energy in the Earth's system and contribute to the greenhouse effect (carbon dioxide, methane, water vapour and nitrous oxides)
• Hadley Cell


  At the equator, hot moist air rises, moves to higher latitudes (30°) and sinks
• Hazard risk


  The probability that a natural hazard will negatively affect a population
• Hotspot


  An area where unusually hot magma breaks through the middle of a plate and travels up to the surface, creating a volcano
• Hurricane


  A tropical storm that hits the USA, Latin America or the Caribbean
• Hydrological hazard


  A hazard caused by the movement of water on the land
• Ice core


  A cylinder of ice extracted from an ice sheet or glacier, which is used to analyse past environmental conditions