1 Natural Hazards

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  • Created on: 09-12-17 16:48
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  • 1 Natural Hazards
    • Natural processes: the natural workings of the Earth and the atmosphere.
    • Natural hazards: the natural process that may cause death/injury to humans.
      • e.g. volcanic eruptions, earthquakes, storms, tsunamis, landslides, floods.
      • No hazard = natural events e.g. floods SEPARATE from people + human activity.
      • Natural hazard / possible disaster = natural events e.g. floods OVERLAP with people + human activity
      • There are 3 main types of natural hazards.
        • 1.) geophysical (geological) hazards
          • they're caused by land and tectonic processes.
            • e.g. volcanoes, avalanches, mudflows, landslides and earthquakes.
        • 2.) atmospheric hazards
          • they're caused by weather and climate.
            • they can be categorised into meteoro- logical and climatological hazards.
              • meteoro-logical hazards are short term.
                • e.g. rain, lightning, wind, snow, hurricanes and tornadoes.
              • climatological hazards are long term.
                • e.g. heatwaves, coldspells and climate change.
        • 3.) hydrological hazards
          • they're hazards from flooding and water.
            • e.g. tsunamis (secondary effect) and coastal / river flooding.
    • Hazard risk: the chance or probability that a natural disaster will occur.
      • there are 3 main factors affecting hazard risk.
        • 1.) vulnerability - the more people that are in areas exposed to natural hazards, the greater the probability they will be affected by a natural disaster; increasing the hazard risk.
          • e.g. urbanisation - over 50% of the world's population now live in cities (from 2008). Densely populated urban areas are at great risk from natural events, such as earthquakes and tropical cyclones.
          • e.g. poverty - in poorer parts of the world, poverty may force people to live in areas prone to natural disaster.
          • e.g. farming - when a river floods, it deposits fertile silt on its flood plain, which is excellent for farming. When people choose to live there they are putting themselves at risk. In low-lying countries many people may live on flood plains.
        • 2.) capacity to cope - natural hazards have to affect human activities to count as a hazard. The better a population can cope with an extreme event, the lower the threat.
          • e.g. the more knowledge people have about what to do in a natural hazard, the less at risk they are.
          • e.g. the more safety precautions put in place, lowers the risk e.g. earthquake proof buildings lowers the risk of people being injured by collapsing buildings.
        • 3.) nature of natural hazards - the type, frequency and magnitude all affect the hazard risk.
          • e.g. type - some natural hazards pose a greater hazard risk than others.
            • tropical storms, volcanic eruptions and tornadoes can all be predicted and monitored, giving people time to evacuate safely. Earthquakes however, cannot be predicted and happen very quickly / suddenly with no warning, so it's much harder to protect people.
          • e.g. frequent - some occur more often than others, increasing the hazard risk, like flooding in the UK.
          • e.g. size / mag. - more severe hazards cause greater effects than less severe ones, like when a mag. 9.0 earthquake struck Japan in 2011, it killed 15,000+ people. But when a mag. 6.3 earthquake struck L'Aquila, Italy around 300 people died.
            • A VEI9 has the potential to kill 10% of the world's population. VEI = volcanic explosivity index.
    • Natural disaster = an event that has caused a large amount of death, destruction and injury.
      • The United Nations (U.N) declare a natural disaster if one or more of the following apply:
        • 10 or more people are killed.
        • 100 or more people are affected
        • a country declares a state of emergency
        • a country appeals for overseas aid.


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