On November 14, 1985, one day after beginning to spew lava, the Nevado del Ruiz volcano in Colombia violently erupted, killing well over 20,000 people as nearby towns are buried in mud, ice and lava.
The volcano is situated in the north-central part of Colombia. Over the centuries, various eruptions caused the formation of large mudflows in the valleys beneath the volcano. When the Nevado del Ruiz went an extended period of time without erupting, people began to build towns over the mudflow areas and glacial ice built up near the volcano’s crater.
In last few months of 1984, activity picked up at the volcano. Multiple tremors were recorded and geologists from around the world traveled to Colombia to observe the situation. The following November, an eruption of steam and ash caused ice, rocks and mud to cascade down the mountain. Scientists, believing that a full-blown eruption was possible, recommended evacuating the area. Their concerns, however, were largely ignored.
On the afternoon of November 13, a major eruption occurred. Ash was sent 30 miles into the air, but still, possibly believing they had more time, few residents evacuated. Later that evening into the morning of the November 14, there were several more powerful eruptions. Lava flowed out of the crater, melting the glacial ice surrounding it and causing massive mudslides.
The town of Chinchina was first to be hit. Approximately 1,100 people were killed when a mudslide overwhelmed the village. The worst scene of destruction was the city of Armero. The wave of mud, rock and ice was nearly 100 feet high as it barreled down on the city. Although it could be heard for a full 30 minutes before it struck, there was little the residents could do to avoid it. Further, many radio reports were instructing the residents to stay in their homes. Close to 20,000 people were buried and killed by the slide.
Overall, the best estimate is that 25,000 lives were claimed by the eruption of the Nevado del Ruiz volcano.