Nevado del Ruiz Erupts: Mudslide Buries 23,000 in Armero

A volcanic eruption melted a glacier and sent a wall of mud, rock, and water cascading down the flanks of Nevado del Ruiz in central Colombia, burying the town of Armero and killing approximately 23,000 people in one of the deadliest volcanic disasters of the twentieth century. The tragedy was made worse by the fact that scientists had warned of almost exactly this scenario for months. Nevado del Ruiz stands 5,321 meters tall in the Andes, its summit capped by glaciers despite sitting only five degrees north of the equator. The volcano had erupted before, most notably in 1845, when a similar mudflow killed about 1,000 people near the same location where Armero was later built. Geologists understood the danger. When the volcano showed increasing signs of activity in late 1984, the Colombian Institute of Geology produced a hazard map in October 1985 that showed Armero directly in the path of potential lahars. The warnings were ignored, delayed, or diluted at every level. Government officials feared causing economic disruption or panic. The Red Cross told residents of Armero to remain calm on the evening of November 13 even as ash fell on the town. A civil defense committee had been formed but lacked equipment, funding, and clear evacuation protocols. At 9:09 p.m., the volcano erupted. The eruption itself was relatively modest, but the heat melted roughly 10 percent of the summit glacier, generating massive lahars that roared down river valleys at speeds up to 60 kilometers per hour. The principal lahar reached Armero at 11:30 p.m., striking a sleeping town with virtually no warning. A wall of mud up to 5 meters deep engulfed the town in minutes. Rescue efforts were hampered by the deep mud, which made it nearly impossible to reach survivors. Images of 13-year-old Omayra Sanchez, trapped in debris with water rising around her, were broadcast worldwide and became a symbol of the disaster. She died after 60 hours.