Nevado Del Ruiz


Nevado Del Riuz, Columbia

  • Location: Nevado Del Ruiz, Columbia
  • Date: November, 13, 1985
  • Time: 3:06


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Places Effected

  • The town of Armero
  • The town of Chinchina
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Before the Eruption

  • At the beginning of November geologists observed that there was a increasing level of seismic activity near Nevado Del Ruiz
  • The signs before the eruption were steam and gasses such as carbon, sulfur dioxide and hydrogen chloride, sulfide and sulfur at the top of the volcano
  • Phreatic eruptions which in included steam, rock fragments and lava which is unusual
  • The most notable of these events was on September,11,1985 which was a ash ejection
  • nearly 1 year there before the eruption there were minor earthquakes and steam eruptions
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  • Scientists said there is no need for evacuation
  • Red Cross ordered evacuation but it was called of close to7p.m. because the ash had stopped falling

The Eruption!!

  • The initial eruption happened at 3:06p.m. and two hours later pumice started to fall on the town of Armero
  • After the red cross evacuation orders being called of, the volcano was still but at 9:08p.m. molten rock started to erupt form the summit creator for the first time all the previous eruptions were steam eruptions
  • The summit ice cap of Nevado Del Ruiz started melting and carried. But a storm covered the summit area so a lot of people were unaware of what was happening. Most of the town was in bed because it was night
  • Melt water mixed with pyroclastic fragments that were erupting creating series of lahars
  • The lahars went 30 mph (50 km)
  • Continued 70 km and hit towns
  • most of the people who lived in the towns swept away or buried by the lahars

Science Behing The Eruption

  • The reason why the eruption happened is because 4 plates run through Nevado Del Ruiz which are the South American, Caribbean, Cocos and the Nazca Plates
  • The second reason is because Nevado Del Ruiz is in the ring of fire, where most of the worlds volcanoes form

Primary Effects

  • At 9:08 pm, on November 13, 1985, Nevado del Ruiz erupted, ejecting dacitic tephra more than 30 kilometers into the atmosphere. The total mass of the amount erupted was 35 million tonnes. The mass of the ejected sulfur dioxide was about 700,000 tonnes, or about 2% of the mass of the erupted solid material.

Secondary Effects

  • The eruption produced pyroclastic flows that melted summit glaciers and snow, generating lahars that raced down river valleys. Water in volcanic lakes tend to be extremely salty and contain dissolved volcanic gases. The lake's hot, acidic water accelerated the melting of the ice; this effect had large amounts of sulfates and chlorides found in the lahar flow.


Armero Lahar - The Human Cost


  • $1,000,000,000 worth of damage
  • 23,000 people died
  • 4,500 people injured
  • 8,000 people homeless
  • 15,000 animals died

Long term effects

  • The government also estimated that over 200,000 people were directly or indirectly affected by the November 13 eruption
  • was 3,723.6 billion (1984 Colombian pesos).
  • 6,000 acres of grain and other crops, as well as many livestock, portions of the agricultural infrastructure, and much prime farmland were effected
  • Portions of roads and railroad tracks, bridges, water and sewer systems, transmission lines, and fuel pipeline were destroyed or damaged
  • approximately 50 schools, as well as many teachers and administrators were impacted


  • Millions of dollars were given to help the people
  • Food was given
  • Tools were given
  • Medical help was given

The Lesson

  • Communication and safety precautions would have saved thousands of lives

Thank You For Listening!

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