Nevado del Ruiz

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Nevado del Ruiz

• Twentieth Anniversary 13 November
  2005

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• Location and Physical Setting

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Location and Physical Setting

• Located North-West of Bogata.
• Located in Columbia Andes.
• East-Cordillera Oriental-Formed From Compressive
  ForcesLimestone, Shale, Sandstone.
• West-Cordillera Occidental-Formed By
  Accreting--Ocean Sediment and Basalt.
• Central CordilleraFormed by Subducted Nazca
  Plate
• Tectonically Active Area.
• Nazca Plate Is Subducted 5 cm/year.
• Northwest Is the Intersection of the Caribbean,
  Cocos, and Nazca Plates.

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Nevado del Ruiz

• Stratovolcano
• Layered Volcano With Alternating Layers of
  Pyroclastic Deposits and Lava.
• Silica Rich Magma.
• Elevation 5,400 Meters.
• Perennially Snow and Ice Covered.
• Ice Thickness 10 to 30 Meters.
• Area Extent 19 Square Kilometers.

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Nevado del Ruiz

• Slope
• Above 4,000 Meters 20 to 30 Percent.
• Geologically Recent Age Deposits.
• Below 4,000 Meters 10 Percent.
• Unknown Age, but Much Older Deposits.
• Symmetrically Extend to the River Plains in East
  and West.
• River Courses Draining the Volcano Have Steep
  V-Shaped Ravines.
• In the East the Guali, Azufrado Lagunillas, and
  Rico Rivers drain to the Magdalena River.
• In the West the Claro, Molinos, and Chinchina
  Rivers drain to the Cauca River.

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Volcanic Activity

• Began Showing Volcanic Activity in November 1984.

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Monitoring Volcanic Activity

• No Money or Much Support From Columbia
  Government.
• Monitoring Came Largely From a Corporation of
  Coffee Growers and From a Hydroelectric Company.
• Office Space in Manizales.
• Scientists
• UN Disaster Relief Office and USGS Gave 3
  Seismographs, But No Technical Assistance.
• Swiss Donated 3 More, and Taught Scientists How
  to Use Them.

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Monitoring Volcanic Activity

• Lots of Infighting Between Local Monitoring
  Office and Columbias National Institute of
  Geology and Mines (INGEOMINAS).
• The Seismic Readings Were Sent To INGEOMINAS in
  Bogata.
• Really Needed Equipment That Would Relay the Data
  Directly to The Office in Manizales.
• September 1985, Seismic Activity Increased Until
  There was a Steam Explosion on September 11, 1985.

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Volcanic Eruption

• November 13, 1985.
• 305 pm Steam Producing Eruption.
• 910 pm Reportedly 2 Explosions Followed By
  Pyroclastic Flows.
• 937 Strongest Eruption Occurred.
• Plume of Gas, Pyroclastics 1,000 M Above the
  Mountain.
• Top of Volcano Covered By 8 M of Pyroclastic
  Material.

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Lahars

• Pyroclastic Surges Eroded and Melted about 10 of
  Ice Cover.
• Water Mixed With Rock Debris and Quickly Moved to
  the Village of Chinchina, 15 Miles From the
  Summit.
• Most Did Not Evacuate.
• 1,000 Dead
• Armero-East
• Two Channels, the Azufrado and the Lagunillas
  River.
• Killed 23,000 People.

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Armero Lahars

• Three PulsesSometime After 11 PM.
• First Pulse Was Mainly Water That Was Displaced
  From a Lake Upstream.
• Second Pulse Destroyed Most of Town.
• Hot Pyroclastic Material Mixed With Soil, Water,
  and debris.
• Ranged From 2 To 5 Meters.
• Third Pulse Was Slower in Velocity and Pushed
  People and Debris Further Downstream.
• Pulses Caused By Damming of Rivers.

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Social Impacts

• Main Impacts to the East
• Estimated Losses 218 Million Dollars.
• Everyone in the Valley Knew Someone Who Was
  Killed.
• Communications Such as Phone Lines, Road
  Networks, and Bridges Destroyed.
• 10,000 Persons Were Left Homeless.
• Two Hospitals Were Destroyed and 50 Schools.
• Experienced Workers Were Lost.
• Armero Served as Regional Center for Financial
  Services, Farm Equipment, and Had a Junior
  College.

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Prevention of Risk Prior To Eruption

• INGEOMINAS Created a Risk Map of the Area.
• First Draft Was Done on October 7, 1985.
• Finalized November 10, 1985.
• 100 Chance that Armero Would Be Destroyed.
• Columbian Congress and Some Local Officials Did
  Not Believe the Risk Was That Great.
• Columbia Civil Defense, Red Cross, and National
  Committee of Regional and Local Organizations Did
  Believe and Planned Procedures For Evacuating
  Places at Risk.

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Prevention of Risk Prior To Eruption

• Civil Defense Operations
• Gathered Emergency Supplies.
• Compiled Census Living Near Rivers at Risk.
• Distributed 1,000s of Public Information
  Pamphlets.
• Uncertain How Many People Got These.
• Uncertain How Well They Understood What a Lahars
  Could Do.
• Conflicting Messages, The Local Catholic Priest
  Urged People to Stay Inside.

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Prevention of Risk Prior To Eruption

• There Was a Call To Evacuate Armero By the Red
  Cross.
• People Were Reluctant Because of Thunderstorm.
• May Have Masked Some Noise From Volcano.
• May Have Been Sporadic Power Outages.
• General Uncertainty of Risk.
• Due To Large Number of Deaths, There Is No Way of
  Knowing If There Was a Systematic, Large Scale
  Effort to Inform the Population.

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After The Eruption

• Strong Push to Educate Population At Risk If
  There Is Another Eruption.
• Siren In Each Neighborhood and Flyers Were
  Distributed Instructing Population To Evacuate
  When Sirens Are Heard.
• One Test and One Potential Incident, But Very Few
  People Evacuated.
• Initial System To Inform Population To Evacuate
  Went Through Many Layers of Government, Which
  Took Over 3 Hours.

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International Changes

• Creation of Volcano Disaster Assistance Program
  (VDAP).
• Countries That Do Not Have the Technical
  Equipment Or Expertise to Monitor An Awakening
  Volcano Can Request It Through USAID.
• Goal Is To Reduce Deaths And Economic Losses.

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• The End