Nevado del Ruiz: The Sleeping Lion of the Andes - History, Tragedy & Resilience
A deep dive into Nevado del Ruiz, the Colombian volcano known for its glacier-capped summit and the devastating 1985 Armero tragedy. Explore its geological formation, historical eruptions, and current monitoring efforts.
Nevado del Ruiz, also known locally as El Mesa de Herveo or “The Sleeping Lion,” is one of the most significant and most notorious volcanoes in South America. Situated in the Central Cordillera of the Colombian Andes, it is the northernmost member of the Ruiz-Tolima volcanic massif. At an elevation of 5,321 meters (17,457 ft), its towering, snow-capped presence has dominated the landscape for millennia, serving as both a source of life-giving water for the fertile valleys below and a recurring source of catastrophic destruction.
1. Geological Formation: A Subduction Giant
Nevado del Ruiz is a classic stratovolcano, formed by the subduction of the Nazca Plate beneath the South American Plate. This plate tectonic interaction creates a “factory” of magma as the oceanic crust is forced deep into the Earth, where it melts and rises to the surface.
Ancestral and Current Structures
The volcanic complex is approximately 2 million years ago, but the current cone—the structure we see today—began forming about 150,000 years ago. It is characterized by an expansive, relatively flat summit (the “Mesa”) and several smaller cones. The core of the volcano is composed of layers of andesitic and dacitic lava flows, alternating with layers of volcanic ash and pyroclastic debris, typical of explosive stratovolcanoes.
The Ruiz-Tolima Massif
Nevado del Ruiz is not isolated. It sits at the intersection of four major fault zones and is part of a larger cluster that includes Nevado del Santa Isabel, Nevado del Cisne, and the Cerro Bravo complex. This proximity means that an eruption at Ruiz is often part of a broader period of regional seismic and volcanic unrest.
2. The Legacy of the Lahars: A Recurring History
While the world remembers 1985, the history of Nevado del Ruiz is a chronicle of devastating mudflows, or lahars. These occur when explosive eruptions provide enough heat to rapidly melt the summit glaciers, sending a mixture of water, ash, and rocks down the river channels.
The Eruptions of 1595 and 1845
- 1595: A major eruption triggered three separate pulses of lahars. These flows travelled down the Gualí and Lagunillas rivers, claiming the lives of 636 people.
- 1845: An even more immense mudflow occurred on February 19, 1845. A massive lahar swept down the Lagunillas River valley for more than 70 kilometers. It killed over 1,000 people and deposited a thick layer of sediment that fertilely enriched the soil.
Tragically, the town of Armero was established in the early 20th century directly on top of these 1845 mudflow deposits—a geological warning that was largely forgotten by the general population and local authorities.
3. The 1985 Armero Tragedy: A World in Grief
The eruption on November 13, 1985, stands as one of the deadliest volcanic events in human history and a haunting case study in failed hazard communication.
Precursors and the Eruption
Starting in late 1984, the volcano began showing signs of unrest: increased seismic activity, fumarole emissions, and phreatic (steam-driven) explosions. Despite warnings from international volcanologists and the creation of a hazard map that accurately predicted the path of future lahars, the local government hesitated to order an evacuation, fearing it would cause unnecessary panic.
The eruption itself was relatively small, measuring only a VEI 3 (Volcanic Explosivity Index). However, it occurred at 9:08 PM, under the cover of a storm. Pyroclastic flows rapidly melted roughly 10% of the volcano’s summit ice cap.
The Destruction of Armero
Within hours, four massive lahars surged down the volcano’s flanks. The flow directed at the Lagunillas River valley reached speeds of 50 km/h. When it hit the town of Armero at 11:30 PM, the lahar was described as a 40-meter-high “wall of noise and mud.” In a single night, 23,000 people perished—approximately 75% of the town’s population. Another 1,000 died in the town of Chinchiná on the opposite side of the volcano.
Omayra Sánchez: The Face of the Disaster
The world’s attention was focused on 13-year-old Omayra Sánchez, who was trapped up to her neck in a mixture of mud and debris. For 60 hours, journalists and rescuers attempted to free her, but without heavy machinery or pumps to lower the water level, their efforts were in vain. She remained courageous, talking to reporters and even singing until she succumbed to gangrene and hypothermia. Her death, captured in a haunting photograph by Frank Fournier, became a symbol of the global community’s impotence in the face of the disaster.
4. Current Status: The “Yellow” Level Alert
Since the 1985 disaster, Nevado del Ruiz has never truly returned to a state of total dormancy. In 2010, the volcano entered a new period of “unrest,” which has continued to this day.
Ongoing Eruptions (2014 - Present)
Since 2014, the volcano has been in a near-continuous state of low-level eruption. This is characterized by:
- Ash Emissions: Frequent ash plumes that often disrupt flights at nearby airports in Manizales and Pereira.
- Seismic Swarms: Intense periods of earthquakes related to the movement of magma and gases within the volcanic conduits.
- Sulfur Dioxide Flux: High levels of gas emission that can be detected by satellites across the continent.
The volcano is currently maintained at a “Yellow Level” (III) of activity by the Colombian Geological Survey, meaning “Changes in the behavior of volcanic activity.” This level signifies that the volcano is unstable and could potentially erupt with little warning.
5. Glacial Retreat and Climate Change
Nevado del Ruiz is one of the few places in Colombia that still hosts permanent glaciers. However, these “eternal snows” are disappearing at an alarming rate.
The Vanishing Ice Cap
In 1985, the glaciated area was approximately 21 km². By 2020, it had shrunk to less than 8 km². This retreat is a “double-edged sword” of heat:
- Volcanic Heat: The ongoing internal activity of the volcano warms the ground from below.
- Global Warming: Atmospheric temperature increases are melting the glaciers from above.
Scientists predict that if current trends continue, the glaciers of Nevado del Ruiz may disappear entirely within the next two decades. Paradoxically, this reduces the volume of water available for future lahars, but it also creates more unstable slopes of loose volcanic debris that can be mobilized by heavy rains.
6. Biodiversity: The High-Altitude Paramo
Despite its destructive reputation, the volcano is the centerpiece of Los Nevados National Natural Park, a vital ecological sanctuary.
The Paramo Ecosystem
The slopes of the volcano (between 3,000 and 4,500 meters) are home to the Paramo, a unique high-altitude moorland. This ecosystem acts like a massive sponge, capturing moisture from the clouds and regulating the water supply for millions of people in the Coffee region of Colombia.
Flora: The Frailejones
The most iconic plant of the Ruiz paramo is the Frailejón (Espeletia). These strange-looking plants have thick, succulent stems and a “crown” of woolly leaves that trap moisture and protect the plant from the intense UV radiation and freezing night temperatures. Some species grow only a few centimeters per year and can live for over 200 years.
Fauna: The Condor and the Hummingbird
The park is one of the last strongholds for the Andean Condor, the largest flying bird in the world. It is also home to the Buffy Helmetcrest hummingbird, which is endemic specifically to the high-altitude volcanic summits of the Ruiz-Tolima massif.
7. Monitoring: The Manizales Observatory
The greatest legacy of the 1985 tragedy is the transformation of Colombia’s approach to volcanic monitoring. The Volcanic and Seismic Observatory of Manizales was established immediately after the disaster and is now one of the most sophisticated in the world.
- Real-time Surveillance: Webcams, gas sensors, and satellite monitoring provide 24/7 data.
- Early Warning Systems: Flash flood and lahar sensors are installed in the Gualí, Lagunillas, and Azufrado rivers to provide crucial minutes of lead time for downstream communities.
- Community Engagement: Regular evacuation drills and educational programs ensure that the local population knows exactly how to respond to alert level changes.
Technical Specifications
| Feature | Data |
|---|---|
| Elevation | 5,321 m (17,457 ft) |
| Crater Diameter | 1 km (Arenas crater) |
| Last Significant Eruption | 1985 (Catastrophic), 2023 (Ash swarms) |
| Primary Hazards | Lahars, Pyroclastic flows, Ash fall |
| National Park | Los Nevados (established 1974) |
| Nearest Cities | Manizales (28 km), Armero-Guayabal (50 km) |
Nevado del Ruiz remains a powerful symbol of the dual nature of our planet: a source of life and beauty, but also a reminder of the need for eternal vigilance and respect for the forces of geology. As the “Sleeping Lion” continues to growl, the world watches, now far better prepared than the fateful night in 1985.