Nevado del Ruiz, in Colombia, is one of the northernmost active volcanoes of the Andean volcanic belt. It has been active for about 1.8 million years. But if ever a moment of such activity has entered history, it is the eruption of November 13, 1985. 40 years ago, the city of Armero was destroyed by the Nevado del Ruiz River.
We are located in the interior of Colombia, in the so-called northern subregion. Armero is 48 km from Nevado del Ruiz and 169 km from Bogota, the country’s capital. The volcano was already there at that time One of the most active in South America. Along with Galeras, it is the most active in the country.
In 1985, Armero, with a population of 29,000, was the capital of the province of Tolima. Today is Guayabal. The tragedy that occurred on the night of Wednesday, November 13 of that year gave a dramatic turn to the history of the municipality. Armero disappeared and about 23,000 people died. The eruption also seriously affected the municipalities of Villamaria and Chinchina.
Signs and warnings were ignored
Already on the 11th, Nevado del Ruiz began to show signs of intense life. “In the previous days the volcano was constantly spewing ash, Its activity has already been reported“, He said Snail Radio Carlos Arturo Osorio, who in 1985 was in charge of the radio station’s transmitters.
He released a lot of ash, as if announcing what he could do. But the volcano remained dormant for 69 years.. Who would have thought that… not the population, but many scientific organizations. Volcanologists had been reporting signs of volcanic activity since December of the previous year.
A mission from the Office of the United Nations Disaster Relief Coordinator (UNDRO) visited the volcano in March 1985. It found that the activity of Nevado del Ruiz was abnormal and consistent with volcanic activity. Typical events preceding a major eruption It recommended starting an active monitoring and risk control plan.
On the eve of the September 19 earthquake in Mexico (more than 40 thousand people died), the mayor of Armero, Ramon Antonio Rodriguez, contacted the editorial office of the Colombian newspaper the time. “Here, about fifteen kilometers from Armero, we have a time bomb, because the Lagunilla River was dammed more than six months ago, and if the Nevado del Ruiz explodes, as they say, Then Armero will lay down the deadBecause the avalanche breaks the dam and destroys us all.”
In October 1985, at the request of the Caldas government, an Italian volcanic expedition analyzed gas samples from the fumarole and terrain. He saw that it was a mixture of carbon dioxide and sulfur dioxide, indicating a direct release of magma to the surface. Italian scientists published a report stating: He warned that the risk of avalanches was unusually high.
What are lahars?
- A lahar is a flow of sediment and water that moves from the slopes of volcanoes. In recent centuries, lahars have destroyed more public or private property than any volcanic process, and have been responsible for the loss of thousands of human lives. Along with falling tephra (emerging solid fragments), it is the main cause of the hazards associated with volcanoes.
Mayor Armero wanted to alert everyone who could do something in the face of such an emergency. He met with Tolima Governor Eduardo Alzate García and several secretaries. He suggested they evacuate the city. He later commented, “They all laughed at me.”
At the beginning of October, the Colombian Parliament also discussed the state of Nevado del Ruiz and the risks to Armero. “One minister dared to say that This war of rumors has caused more damage than the ash the volcano can spew. “During the eruption,” El Tiempo recalls today.
As in 1595 and 1845
In November 1985, volcanic activity increased again as magma approached the surface. The volcano began to release large and increasing amounts of sulfur-rich gases, mainly sulfur dioxide. the The degassing of magma caused an increase in pressure inside the volcanodirectly into the space above the magma, which eventually led to a volcanic eruption.
Experts already know a lot about what the Nevado del Ruiz eruptions were like: Mostly explosiveBut it has a moderate volcanic eruption index (VEI), ranging from 3 to 4 on a scale of 0 to 8. When this volcano erupted, it produced rapid streams of lava flows, which are a mixture of rock and hot gas.
These eruptions, even moderate-sized ones, melt the volcano’s extensive ice cover, Generating mudslides and massive mud and debris flows. These represent a serious threat to human life and the environment. This actually happened in 1595 and 1845, and happened again on November 13, 1985.
“That night I was alone in my hut when I felt something fall at the door. I thought it was a soldier leaning on the sentry box, but when I went out I didn’t see anything. Then I heard stones and firestones falling (…) I realized it was Nevado del Ruiz. I blessed myself and thought: This is as far as I’ve come.” Osorio says today.
Moderate but destructive eruption
The volcano erupted at 9:09 p.m., spewing dacitic tephra more than 30 kilometers into the atmosphere. The total mass of explosive material, including magma, It was 35 million tons. The mass of expelled sulfur dioxide amounted to about 700 thousand tons.
That night was a moderate volcanic eruption (VEI 3). The eruption produced lava flows that melted glaciers and snow, generating four lahars that ran down the slopes of the volcano. The largest of these flows completely destroyed Armero. For years there has been reckless use of the land and many homes have been built in the likely path of collapses. A river, first of water, then of mud, and finally of lava, destroyed the city.
The 300-ton rock, which was dragged for a distance of 16 kilometers, gives an idea of the strength of that torrent. “I felt Strong sulfurous smellThe fog was low and ash continued to fall. “After the big bang, there were two or three other emissions that were smaller, but equally powerful,” Osorio told the Colombian radio station.
3,000 more deaths in Villamaria and Chinchina
According to the Colombian Disaster Studies Commission, at least 23,000 people died (other sources citing local media) They raise the number to 25 thousand). In Villamaría and Chinchina, in Caldas province, there were another 3,000 deaths.
“Complete destruction. Farms, livestock, homes, everything is covered… as if the ground had become a pavement.”
And the next day, when the sky cleared, And witness the total devastation Disappeared farms, livestock, houses, everything is covered. It was a wasteland, as if the land had become a sidewalk,” Osorio says today.
The Nevado del Ruiz is considered a volcanic disaster The bloodiest of the twentieth century in South America And the fourth largest in the world since the sixteenth century.
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