Armero is a city in Colombia which was wiped off the map after a catastrophic volcanic eruption in 1985. Roughly 2/3 of the population of 30,000 was killed, with some estimates being even higher. The tragedy of what happened at Armero is that many scientists and officials agree that the disaster could have been averted by evacuating the city. Armero is often used as an example to illustrate the need for effective early warning systems and evacuation protocols in areas where volcanic activity is likely to occur.
The Nevada del Ruiz volcano which caused the disaster at Armero had been known to erupt before, triggering flows of volcanic ash and mud known as lahars. In 1595, the volcano erupted and killed large numbers of people, and it did the same thing 250 years later. As early as 1984, geologists noticed that the volcano had become much more active, triggering steam explosions and earthquakes, and they warned officials to evacuate the area.
Predictions of an impending eruption peaked in early November, 1985, but officials continued to state that the situation was under control, and citizens had nothing to fear. Although some people did heed the obvious signs and fled the area, many more stayed put, confident that government officials knew what they were doing. When the volcano erupted on 13 November, 1985, the results were catastrophic.
The eruption melted the volcano's ice cap, triggering a lahar of volcanic ash, water, and debris which was both extremely hot and very violent. The lahar crashed through a dam on the Lagunilla River, triggering a flood which overwhelmed the city of Armero. Huge rocks torn from the bed of the river rumbled through the city, crushing everything in their path, while the lahar deposited layers of silt, ash, and other debris on the city.
When rescue workers arrived at the city, they were reportedly horrified by the bodies of dead and injured people and animals at the site. Where Armero had once been, there was a vast muddy plain dotted with rooftops. Victims were trapped inside and underneath the rubble, including a young girl named Omayra Sanchez, who became a figure of public interest when rescuers discovered that she was trapped in such a way that she could not be pulled out. After three days of very public agony in the ruins of Armero, Omayra died, and her photograph was transmitted around the world.
This South American version of Pompeii made international headlines both because of the scope of the damage and because of its preventability. Many public officials faced heavy criticism in the wake of the Armero tragedy, leading to reforms in the way that the risk of a volcanic eruption is handled around the world, as no nation wanted to host a repeat of Armero.