Armero, situated close to the River Magdelena, was the home of 29,000 people until November 13th 1985 when the nearby Volcano Nevado del Ruiz erupted.
The pyroclastic flows leaving the volcano melted nearby glaciers and caused a mudslide. Two hours later the mud arrived at Armero, covering the town and killing 20,000 of its inhabitants. The first rescue workers didn’t arrive for over 12 hours, held back by the mud-field which was almost impossible to cross.
Today Armero is abandoned, its surviving residents having created a new town further up the river, outside the danger area.