Case study : lahar

• When did the Nevado del Ruiz volcano erupt?

  13 November 1985
• How long had the Nevado del Ruiz volcano been dormant before its eruption?

  140 years
• What natural phenomenon was created by the eruption of Nevado del Ruiz?

  Lahars
• What caused the lahars to form during the eruption?

  Hot ash and rock melted snow and ice
• How deep were the lahars that formed from the eruption?

  Up to 40 m deep
• What was the maximum speed of the lahars?

  Up to 50 kph
• How far was the town of Armero from the crater of Nevado del Ruiz?

  74 km
• How long did it take for the lahar to reach the town of Armero?

  Two and a half hours
• What was the consequence of the lack of timely warning for the people of Armero?

  Over 23,000 people were killed
• What percentage of the town of Armero was washed away by the lahar?

  85 percent
• Why is the Nevado del Ruiz eruption considered one of the worst volcanic disasters in history?

  Due to the high death toll and destruction
• What are the key details of the Nevado del Ruiz eruption case study?

  • Eruption date: 13 November 1985
  • Dormant for 140 years
  • Created lahars from melted snow and ice
  • Lahars up to 40 m deep, 50 kph speed
  • Town of Armero: 74 km from crater
  • Reached Armero in two and a half hours
  • Over 23,000 fatalities
  • 85% of the town washed away