Mudslide Buried Armero and 23,000 Residents in 1985
Four decades after the eruption of Nevado del Ruiz, the volcanic debris field that consumed the Colombian city remains a marker of catastrophic risk for mountain communities.
By Sakura Ellis ·
On November 13, 1985, a volcanic mudslide swept through the town of Armero in Colombia, killing approximately 23,000 people.
The disaster occurred when a rapid flow of volcanic ash, water, and debris from Nevado del Ruiz descended into the city, overwhelming the population before they could evacuate. The event stands as one of the deadliest volcanic eruptions in modern history.
The mudslide demonstrated the specific dangers facing settlements located in river valleys beneath active volcanoes. While the volcano had shown signs of unrest, the speed of the flow left limited time for organized rescue efforts.
In the decades following the tragedy, Armero remains largely a memorial site, with the ruins of the city preserved under the gray sediment. The site serves as a reference point for geologists studying pyroclastic density currents and for urban planners assessing risk in similar terrain.
Historical records from the date also note other major events. In 1775, General Richard Montgomery led American troops to capture Montreal during the Revolutionary War. In 1956, the U.S. Supreme Court affirmed that Alabama bus segregation laws were illegal.
In 1971, the Mariner 9 space probe entered orbit around Mars, becoming the first spacecraft to do so. In 2015, coordinated attacks by Islamic State militants in Paris resulted in 130 deaths, marking the worst attack on French soil since World War II.
On the current date, Friday, November 13, 2026, several public figures also mark birthdays. Actor Joe Mantegna turns 79, and Republican U.S. Senator Dan Sullivan of Alaska turns 62.
