Nevado del Ruiz

The volcano grew from many eruptions, one layer on top of another.

It has been built up and broken down again and again.

The SGC says the volcanic complex has a history of 1.8 million years, and the present volcano is about 66,000 years old. Three stages, called Ancestral Ruiz, Old Ruiz and Ruiz, each built a cone and then partly destroyed it.

The volcano is long and somewhat flattened, about 15 kilometers across at its base. Its active crater, Arenas, is 870 by 830 meters wide and 247 meters deep.

Ruiz sits on the same basement as Cerro Bravo, at a complex intersection of four fault groups. Three stages (Ruiz Ancestral, Ruiz Viejo and Ruiz) alternately built and destroyed three edifices, producing lavas, pyroclastic flows and surges, debris avalanches, fall deposits, lahars and domes; the products are mainly two-pyroxene andesites (SGC).

The complex has a 1.8-million-year history; the volcano itself is about 66,000 years old, and its activity over the last 14,000 years has been mainly explosive, with Volcanic Explosivity Index values of 3 to 4 on a scale of 0 to 8 (SGC fact sheet).

Rivers begin on the volcano's slopes.

Scientists watch the volcano every day to keep people safe.

Rivers start on the volcano's slopes and run down narrow, deep, steep valleys. The Gualí, Lagunillas and Recio flow to the Magdalena River, and the Chinchiná flows to the Cauca.

In 1985 an eruption sent fast mudflows called lahars down valleys from the volcano. Since then the SGC has watched the volcano constantly, and it gives warnings with alert levels.

Drainage is radial and eccentric: the Gualí, Lagunillas and Recio rivers (Magdalena tributaries) and the Chinchiná (a Cauca tributary) rise on the edifice in narrow, deep, steep valleys (SGC).

In its eruption of 13 November 1985, the main phenomena were lahars and ash fall; the SGC has monitored the volcano permanently since 1985. Since 2010 it has twice raised the activity level to orange; the most recent orange period ran from 30 March to 27 June 2023.

Around the volcano grow cold grasslands and cloud forests.

Spectacled bears and mountain tapirs live in the park.

The volcano rises in Los Nevados National Natural Park, created in 1974. Its high lands include páramo (high mountain grassland), wetlands, high Andean forest and glaciers.

The park protects the mountain tapir, the spectacled bear, the pudu deer and the puma. Andean condors and the yellow-eared parrot fly here, and the park also protects the wax palm.

Los Nevados National Natural Park (1974, 61,420 ha) covers the Ruiz massif with Santa Isabel and Tolima; it protects páramo, high Andean wetlands and high Andean forest, with superpáramo and glacier above, and the upper basins of the Chinchiná, Otún, Quindío and Combeima rivers (Parques Nacionales Naturales de Colombia, 2019).

Conservation targets include Polylepis sericea, the rufous-fronted parakeet, the Andean duck and the wax palm (Ceroxylon quindiuense); mammals include the mountain tapir, spectacled bear, pudu, white-tailed deer, oncilla and puma; birds include the yellow-eared parrot and the Andean condor.

The air is thin high on the volcano, and it is cold.

Only visit with a grown-up, on the paths that are allowed.

The SGC says visitors to the park's northern area enter at about 4,100 meters, and the allowed route reaches about 4,450 meters. Parks Colombia sets the rules for entry, so check them first.

The CDC says anyone sleeping at 2,450 meters or higher without getting used to the height first can get altitude sickness, and it says to follow local officials' advice about volcanoes.

Northern access: from the La Esperanza - El Ocho road toward Murillo, about 18 km to the Brisas entrance at 4,100 m; the authorized visitor route extends to 4,450 m. Entry requirements and restrictions are set by Parques Nacionales Naturales de Colombia (SGC).

CDC: unacclimatized travelers going to a sleeping altitude of 2,450 m or more are at risk of altitude illness; children are as susceptible as adults. Near volcanoes, follow local officials' advice on preparing, sheltering or evacuating.