Volcanoes

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  • Created by: Rachelezy
  • Created on: 10-10-18 13:06
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  • Volcanoes
    • Basic Information
      • Earth's crust through which lava, ash and gases erupt.
      • Closely associated with plate margins
      • Hot magma and gases push up from mantle to the Earth's crust
        • Lava = Magma that reaches the Earth's surface
      • Around 1900 volcanoes are considered to be active
    • Primary Hazards
      • Lava Flows
        • Streams of lava
        • Have erupted from a volcano onto the Earth's surface
        • Takes years to cool completeley
        • Move slowly - Not very threatening to humans
        • Destroy everything in their path
      • Pyroclastic Flows
        • One of the greatest volcanic hazards
        • Mixture of dense hot rock, lava. ash, and gases ejected from a volcano
        • Destroy everything in their path
        • Move very quickly and can reach up to 700'C
          • Can travel at 100 km per hour
      • Tephra and Ash falls
        • Tephra -Pieces of volcano rock and ash which blast into air during an eruption
        • Larger pieces tend to fall near the volcano
          • Can cause injury and death (as well as damaging structures)
        • Ash falls - Very disruptive
          • Covers everything causing poor visibility and slippery roads
          • Roofs may collapse due to its weight
          • Engines may get clogged or stop working
      • Gas Eruptions
        • Released into atmosphere during eruption
          • Potential hazard to people, animals and structures
        • Water Vapour (80%)
        • Carbon Dioxide
        • Sulphur Dioxide
        • Can travel for thousands of kilometres
    • Secondary Hazards
      • Lahars
        • Masses of rock, mud and water that travel quickly down the side of a volcano
        • Travel too fast for people to outrun
        • Caused when an eruption quickly melts snow and ice
          • Or heavy rainfall during or after and eruption
      • Jokulhlaup
        • Glacial outburst floods
        • Dangerous because they suddenly release large amounts of water, rock, gravel and ice that can catch people unaware.
        • Flood and damage land and alnd structures
        • Heavy and sudden floods made by an eruption melting ice and snow in a glacier

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