CGP Volcanic Hazards

• Volcanic Hazards


  Hazards that occur due to volcanic activity
• Volcanic Hazards


  • Usually occur near plate margins
• Volcanic activity at plate margins

  1. Plates are pulling apart, forming ocean ridges

  2. Plates are subducting, causing melting and formation of volcanoes
• Andesitic and rhyolitic lava


  • Cooler and more viscous, flow less easily
  • Eruptions are usually less frequent and more explosive
• Basaltic lava


  • Flows quickly, forming shield volcanoes with gentle slopes
• Primary volcanic hazards

  • Pyroclastic flows
  • Lava flows
  • Volcanic gases
• Pyroclastic flow

  A mixture of superheated gas, ash and volcanic material that flows down the sides of a volcano at high speed
• Lava flow


  Lava that flows from a volcanic vent down the side of the volcano
• Volcanic gases like carbon dioxide and sulfur dioxide can be harmful to humans and animals if breathed in
• Volcanic fallout


  Material ejected from a volcano during an eruption and falls back to the ground
• Secondary volcanic hazards

  • Lahars (volcanic mudflows)
  • Acid rain
• Lahar


  Volcanic material mixed with large amounts of water, flowing rapidly downslope
• Acid rain


  Volcanic gases reacting with water vapour in the atmosphere, forming weak acids that fall as rain
• Magnitude


  The size or scale of a volcanic event, from small lava flows to huge explosive eruptions
• Volcanic Explosivity Index (VEI)


  A scale from 0 to 8 that measures the magnitude of a volcanic eruption based on the amount of material ejected and the height it is blasted
• Frequency


  How often a volcano erupts, from once every 100,000 years to several times per year
• Predictability


  How regularly a volcano erupts, which can help scientists predict when the next eruption may occur
• Scientists monitor earthquakes and changes in the shape of a volcano to predict when an eruption may be imminent