page_title: Nevado del Ruiz
section_title: Current threats and preparedness
hierarchical_section_title: Nevado del Ruiz / Current threats and preparedness
caption_attribution_description: English: Photo of Nevado del Ruiz taken on approach to El Dorado International Airport, Bogota. Nevado del Tolima is visible in the background on the left. Approximate altitude of photo: 23,550 ft.
context_page_description: The Nevado del Ruiz, also known as La Mesa de Herveo is a volcano located on the border of the departments of Caldas and Tolima in Colombia, about 129 kilometers west of the capital city Bogotá. It is a stratovolcano composed of many layers of lava alternating with hardened volcanic ash and other pyroclastic rocks. Volcanic activity at Nevado del Ruiz began about two million years ago, since the Early Pleistocene or Late Pliocene, with three major eruptive periods. The current volcanic cone formed during the present eruptive period, which began 150 thousand years ago.
  The volcano usually generates Vulcanian to Plinian eruptions, which produce swift-moving currents of hot gas and rock called pyroclastic flows. These eruptions often cause massive lahars, which pose a threat to human life and the environment. The impact of such an eruption is increased as the hot gas and lava melt the mountain's snowcap, adding large quantities of water to the flow. On November 13, 1985, a small eruption produced an enormous lahar that buried and destroyed the town of Armero in Tolima, causing an estimated 25,000 deaths.
context_section_description: The volcano continues to pose a serious threat to nearby towns and villages. The most likely hazard is small-volume eruptions, which might destabilize glaciers and trigger lahars. Despite the significant retrenchment of the volcano's glaciers, the volume of ice atop Nevado del Ruiz and other volcanoes in the Ruiz–Tolima massif remains large. Melting merely 10% of the ice would produce mudflows with a volume of up to 2,000,000 cubic meters (70,629,333 cu ft)—similar to the mudflow that destroyed Armero in 1985. Such lahars can travel up to 100 kilometers (62 mi) along river valleys in a matter of few hours. Estimates show that up to 500,000 people living in the Combeima, Chinchiná, Coello-Toche, and Guali valleys are in danger, and 100,000 of these are considered to be at high risk. Lahars pose a threat to nearby towns of Honda, Mariquita, Ambalema, Chinchiná, Herveo, Villa Hermosa, Salgar and La Dorada. Although small eruptions are more likely, the two million-year eruptive history of the Ruiz–Tolima massif includes numerous large eruptions, indicating that the threat of a large eruption cannot be ignored.
  A large eruption would have more widespread effects, including the potential closure of Bogotá's airport due to ashfall.
  As the Armero tragedy was exacerbated by the lack of early warnings, unwise land use, and the unpreparedness of nearby communities, the government of Colombia created a special program (Oficina Nacional para la Atencion de Desastres, 1987) to prevent such incidents in the future. All Colombian cities were directed to promote prevention planning in order to mitigate the consequences of natural disasters, and evacuations due to volcanic hazards have been carried out. About 2,300 people living along five nearby rivers were evacuated when Nevado del Ruiz erupted again in 1989. When another Colombian volcano, the Nevado del Huila, erupted in April 2008, thousands of people were evacuated because volcanologists worried that the eruption could be another "Nevado del Ruiz".
  In 2006, heavy rains on Ruiz sent a mudslide down the Chinchiná River, killing nine youths aged 12–19 on a scouting expedition near the volcano.
caption: Photo of Nevado del Ruiz taken on approach to El Dorado International Airport, Bogotá. Nevado del Tolima is visible in the background on the left. Approximate altitude of photo: 7,180 m (23,550 ft).
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