Natural Hazards 1

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  • Created on: 08-05-22 14:04
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  • Natural Hazards 1
    • Natural Hazards
      • It is an extreme natural event that can cause loss of life and extreme damage to properties.
      • Types of natural hazards are: Tectonic, Atmospheric, Geomorphical and biological.
        • Tectonic: earthquakes and volcanoes.
        • Atmospheric: hurricanes
        • Geomorphological: flooding and landslides
        • Biological: forest fires
      • A hazard risk is the probability that a natural hazard will actually affect a population.
        • Factors affecting hazard risk: social, environmental and economic.
          • Other: urbanisation, population growth, wealth, climate change, poverty and hazardous living conditions.
    • The Earth
      • The 4 layers: inner core, outer core, mantle, crust
        • OCEANIC CRUST: Under seas/oceans, thinner (8-12km), HEAVY Basaltic rock
          • Can be subducted
        • CONTINENTAL CRUST: On land, thicker (30-65km), LIGHT Granitic rock
          • Less often destroyed.
    • Tectonic Hazards
      • Continental drift theory is the idea that the plates slowly shift their position on the earth.
        • Tectonic plates are the Earth's crust split up into multiple large slabs.
        • Convection currents is the transfer of heat from the core to the crust.
          • 1. Core heats up magma in mantle, hot magma less dense than surroundings so it rises.
            • 2. When it reaches the top it cools. Becomes less dense and therefore sinks back down.
              • 3. Heated up again, cycle continues.
                • 4. Plates are pushed and pulled by CC.
      • Plate boundaries: Constructive, Collision, Destructive, Conservative
      • Tectonic hazards occur on plate margins.
        • Earthquakes are found along all types of plate margins.
          • We can measure earthquakes by using the Richter Scale, which measures the magnitude of a tremor.
            • By using an instrument called a seismograph.
    • Plate margins
      • Constructive: 1.Plates pulled apart by CC, magma rises between them and forms volcanoes.
        • 2.Lava cools and solidifies= new crust.
          • 3.Movement of crust causes small earthquakes
      • Destructive:1.Plates move towards eachother. Heavier oceanic plate move under continental.
        • 2.Plates rub together causing severe earthquakes.
          • 3.Friction and heat from mantle heats rock, magma rises and violent colcanic eruption happens.
      • Conservative: 1. Plates try to slide past eachother, plates stick together.
        • 2.Huge amounts of pressure build up, pressure release causes violent earthquake.
          • 3.Plates move on a few milimetres. No volcanic activity.


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