The Eruption of Nevado Del Ruiz Volcano Colombia, South America, November 13, 1985

On November 13, 1985, catastrophic mudflows swept down the slopes of the erupting Nevado del Ruiz volcano, destroying structures in their paths.

Various estimates of deaths ranged as high as 24,000 residents.

Though the nature and extent of risk posed by the mudflows to local communities were well documented before the event and extensive efforts had been made to communicate this information to those at risk, the affected communities were caught largely unaware. This volume analyzes the disaster's many aspects: the extent, constitution, and behavior of the mudflows; the nature of damage to structures; the status of the area's disaster warning system; and the extent of the area's disaster preparedness, emergency response actions, and disaster relief efforts?both at the time of the disaster and in the first few months following the event. Table of ContentsFront MatterExecutive Summary1 Physical Setting and Geologic History2 The November 13, 1985 Eruption and Subsequent Lahars3 Performance of Various Structures along the Lahar Paths4 Preeruption Awareness and Preparedness5 The Warning Period6 Disaster Impacts7 The Recovery Program8 Posteruption Hazard Watch and Disaster PlanningReferencesAppendix A Geologic Setting and Prehistoric Volcanic ActivitiesAppendix B Recommendations for Improving the Existing WarningSystem for an Impending Eruption of the Nevado del Ruiz Volcano,Colombia, South America: An Advance Report, January/February 1986