Volcanic Hazards

• 6 primary hazards caused by volcanic eruptions are:

  1. Lava Flows
  2. Pyroclastic Flows
  3. Tephra
  4. Ash Fall
  5. Volcanic gas emissions
  6. Lahars
• How does the impact of lava flows pose a hazard for people and infrastructure?

  Destroys everything in its path, including buildings, infrastructure, and vegetation. Lava flows can also cause fires.
• How do pyroclastic flows pose a hazard to people and infrastructure?

  Extremely destructive due to their high speed and temperature, they can obliterate anything in their path and are often fatal to humans and animals.
• How do tephra and ash fall pose hazards to people and infrastructure?

  Can cause respiratory problems, contaminate water supplies, damage machinery, collapse roofs, and disrupt air travel.
• How do volcanic gas emissions pose as a hazard?

  Can cause air pollution, respiratory issues, and even lead to climate change by altering atmospheric conditions.
• How do lahars (mudflows) impact / pose as hazards to people?

  Can bury communities, destroy infrastructure, and contaminate water supplies.
• What are the 6 secondary hazards caused by volcanic eruptions?

  1. Volcanic Landslides
  2. Tsunamis - Sea waves can be generated by volcanic activity, particularly by submarine eruptions or volcanic landslides.
  3. Flooding - The melting of ice or snow on a volcano during an eruption can lead to sudden floods. (can be caused by lahar)
  4. Climate Effects - Large eruptions can inject ash and sulfur dioxide into the stratosphere
  5. Lahar
  6. Acid Rain - when the eruption emits sulphur dioxide and it combines with atmospheric moisture acid rain occurs
• A secondary hazard of a volcanic eruption is the increase of ash and sulfur dioxide in the stratosphere. This causes global dimming and cooling. This is a hazard because of what?


  it can potentially disrupt weather patterns and agriculture
• Long-term hazards/impacts of volcanic eruptions include:?

  1. Soil and Water contamination - deposition of volcanic ash and the release of gases can make agricultural land infertile and water sources undrinkable
  2. Health Issues - long term exposure to volcanic ash and gases can cause chronic respiratory problems and other health issues
• Lahars - melted snow and ice as a result of an eruption combined with volcanic ash forms mud flows that move down the course of river valleys at high speeds. In 1985 lahar formed after Nevado Del Ruiz erupted. The lahar destroyed a Colombian town in Armero. Only 25% of the population survived (around 7200 people).
• One example of flooding was in Iceland in 1996 when the Grimsvotn volcano erupted
• One example of a volcano causing a tsunami is the eruption of Karatoa (Indonesia) in 1883. Tsunamis from this eruption killed around 36000 people.