Geography

• A natural hazard can be defined as a natural event that has a social impact
• Types of natural hazards

  • Tectonic hazards (volcanoes, tsunamis, earthquakes)
  • Biological hazards (forest fires)
  • Geomorphological hazards (flooding, mudslides, rockslides)
  • Atmospheric hazards (hurricanes, tornadoes, lightning, rain)
• Why do people live in hazardous areas?


  • They don't want to leave
  • They believe defences will protect them
  • They don't believe the hazard will occur
  • Economic reasons (jobs, facilities)
  • Social reasons (don't know where to go, language barriers)
• Human activity impacts climate change


  Leads to more flooding and extreme weather events
• Tectonic plates


  • They are part of the Earth's crust and are constantly moving
  • Oceanic crust is thin and less dense than continental crust
  • Destructive plate margin (continental-continental, continental-oceanic)
  • Conservative plate margin (plates move against each other)
  • Constructive plate margin (plates move away from each other)
• Primary effects


  First effect of a natural hazard on the population
• Secondary effects


  After effects of a natural hazard over a longer time scale
• Immediate response


  How people react as the event is happening and immediately afterwards
• Long-term response


  How people react in the weeks or months after the event
• High Income Country (HIC)


  Country with Gross National Income over $12,000 per person
• Low Income Country (LIC)


  Country with Gross National Income less than $12,000 per person
• Earthquakes in HIC


  • Chile (8.8 Richter, $30 billion cost)
  • Italy (6.3 Richter, $11 billion cost)
• Earthquake in LIC


  • Nepal (7.9 Richter, $5 billion cost)
• Predicting volcanic eruptions is easier than predicting earthquakes
• Monitoring volcanic eruptions


  • Measure temperature of local water
  • Monitor gases being released
  • Monitor changes in local gravity
  • Use satellites to monitor ground changes
• Protecting against earthquakes


  • Map affected areas
  • Locate important buildings away from affected areas
  • Fasten down furniture
  • Educate local population
  • Stockpile food and medical supplies
  • Practice earthquake drills
• Mapping areas affected by earthquakes


  • Identify areas that might be affected so hospitals and important buildings can be situated safely
  • Ensure buildings have furniture fastened down to reduce damage from flying objects
  • Educate local population on what to do in an earthquake
  • Stockpile food and medical supplies
  • Have earthquake drills to practice response
• Protecting against earthquakes


  • Use new technology to build earthquake-resistant buildings
  • Predicting earthquakes is much harder than other tectonic hazards, no clear warning signs
• Some people think animals can sense when earthquakes are about to occur and their behavior will change
• Smartphones have accelerometers and GPS which can detect earthquakes minutes before they occur
• Pressure belts


  Important factors affecting global weather
• Climate cells


  Important factors affecting global weather
• Differences in the angle of the sun's energy hitting the Earth causes variations in heating at the equator and poles
• Features of global atmospheric circulation


  • Descending cool dry air and high pressure by the poles
  • Rising warm moist air and low pressure
  • Seasonal movement of cells north and south
• Tropical storms can occur in different locations at different times of year
• Hurricanes, cyclones, typhoons


  Differ in where they start - Atlantic/E Pacific, Indian/S Pacific, W North Pacific respectively
• Conditions for tropical storm formation


  • Low altitude
  • High temperature
  • High sea temperature
  • Sea 60-70m deep
• Tropical storm categories


  Refer to wind speed in km/h
• Tropical storm formation


  1. Air over warm oceans heated and rises under low pressure

  2. Air brings more air and moisture, resulting in strong winds

  3. Coriolis effect causes air to spin around calm center

  4. Evaporated moisture condenses and cools, drawing more moisture upwards

  5. Large clouds and heavy rainfall form
• Eye of the storm


  Dry and calm as cold air sinks, stops gaining energy from water
• Climate change effects on tropical storms


  • Increased temperatures, sea levels, moisture in air leads to more severe storms, higher rainfall, and greater destructive impact
  • Storms becoming more frequent and unpredictable
• Reducing effects of tropical storms


  • Plan storm shelters
  • Provide disaster supply kits
  • Educate public on response plans
  • Install storm shutters, drains, sea walls, reinforce buildings
  • Remove trees that could damage buildings
• National Hurricane Center and NOAA use satellites, aircraft, and supercomputers to monitor and predict tropical storms
• UK extreme weather hazards


  • Snow and extreme cold
  • Strong winds from hurricanes
  • Droughts
  • Extreme rainfall and flooding
• Extreme weather in UK becoming more frequent and varied due to climate change caused by human activities
• Evidence for climate change


  • Increase in global temperature
  • Decrease in global sea ice and land ice
  • Increase in sea levels
• Natural causes of climate change


  • Changes in Earth's tilt, orbital path, and wobble over long timescales
  • Variations in solar activity and volcanic eruptions
• Greenhouse effect


  Greenhouse gases absorb outgoing long-wave radiation, trapping heat
• Greenhouse gases


  • Carbon dioxide
  • Methane
  • Nitrous oxides
  • Water vapour
• Sources of greenhouse gas emissions


  • Combustion of fossil fuels (over 50% of global emissions)
  • Agriculture (around 20% of global emissions)
  • Deforestation