The Armero Tragedy of 13 November 1985, When a Predicted Lahar Killed 23,000 People
When Nevado del Ruiz erupted on 13 November 1985, its melting ice cap sent lahars — volcanic mudflows — down river valleys onto the sleeping town of Armero, Colombia. Around 23,000 of its 29,000 inhabitants died. Hazard maps had predicted the flow path almost exactly; evacuation never happened.
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