Volcanic Hazards

• We only get volcanoes at constructive and destructive plate boundaries, but they have very different characteristics.
• Nuees ardentes (or pyroclastic flow) is formed from a mixture of hot gases and tephra. They flow down the side of a volcano at speeds over 700km/h.
• Lava flows are molten rock flowing onto the surface. Acid lava solidifies very quickly, but basaltic lava flows more before solidifying.
• Lahars are formed by volcanic ash mixing with water flowing downhill. They are volcanic mudflows from snowmelt or heavy rainfall.
• Gases such as carbon dioxide, carbon monoxide, sulphur dioxide and chlorine are emitted by a volcano.
• Tephra is solid matter ejected by a volcano into the air.
• Magnitude is measured using the volcanic explosivity index (VEI).
• Spatial distribution is where things are.
• Randomness is how likely.
• Magnitude is size.
• Frequency is how often.
• Regularity is patterns and frequency.
• Predictability is how predictable.
• Primary effects of volcanic hazards:

  • Toxic gas
  • Lava flows
  • Pyroclastic flows
  • Lava bombs
  • Ash on roofs
  • Earthquakes
  • Tephra
• Secondary effects of volcanic hazards:

  • Lahars
  • Acid rain
  • Tsunamis
  • Landslides
  • Weather changes
  • Flooding
  • Deforestation