The Armero tragedy (Spanish: Tragedia de Armero [tɾaˈxeðja ðe aɾˈmeɾo]) occurred following the eruption of the Nevado del Ruiz stratovolcano in Tolima, Colombia, on November 13, 1985. The volcano's eruption after 69 years of dormancy caught nearby towns unprepared, even though volcanological organizations had warned the government to evacuate the area after they had detected volcanic activity two months earlier.
As pyroclastic flows erupted from the volcano's crater, they melted the mountain's glaciers, sending four enormous lahars (volcanically induced mudflows, landslides, and debris flows) down the slopes at 50 km/h (30 mph). The lahars picked up speed in gullies and engulfed the town of Armero, killing more than 20,000 of its almost 29,000 inhabitants. Casualties in other towns, particularly Chinchiná, brought the overall death toll to 23,000. Footage and photographs of Omayra Sánchez, a young victim of the disaster, were published around the world. Other photographs of the lahars and the impact of the disaster captured attention worldwide and led to controversy over the degree to which the Colombian government was responsible for the disaster. A banner at a mass funeral in Ibagué read, "The volcano didn't kill 22,000 people. The government killed them."
The relief efforts were hindered by the composition of the mud, which made it nearly impossible to move through without becoming stuck. By the time relief workers reached Armero twelve hours after the eruption, many of the victims with serious injuries were dead. The relief workers were horrified by the landscape of fallen trees, disfigured human bodies, and piles of debris from entire houses. This was the second-deadliest volcanic disaster of the 20th century, surpassed only by the 1902 eruption of Mount Pelée, and is the fourth-deadliest volcanic event recorded since 1500.
The event was a foreseeable catastrophe exacerbated by the populace's unawareness of the volcano's destructive history; geologists and other experts had warned authorities and media outlets about the danger in the weeks and days leading up to the eruption. Hazard maps for the vicinity were prepared but poorly distributed. On the day of the eruption, several evacuation attempts were made, but a severe storm restricted communications. Many victims stayed in their houses as they had been instructed, believing that the eruption had ended. The noise from the storm may have prevented many from hearing the sounds of the eruption until it was too late.
Nevado del Ruiz has erupted several times since 1985, and continues to threaten up to 500,000 people living along the Combeima, Chinchiná, Coello-Toche, and Guali river valleys. A lahar (or group of lahars) similar in size to the 1985 event might travel as far as 100 km (60 mi) from the volcano and could be triggered by a small eruption. To counter this threat, the Colombian government established a specialized office which administers the national system for identification, prevention, preparedness and management of natural disasters, the National Unit for Management of Disasters Risk (Sistema Nacional de Gestión del Riesgo de Desastres). The United States Geological Survey also created the Volcano Disaster Assistance Program and the Volcano Crisis Assistance Team, which evacuated roughly 75,000 people from the area around Mount Pinatubo before its 1991 eruption. All Colombian counties, by law, have a territorial plan that includes the identification of natural threats, treatment for building permits and preparedness for the prevention and management of natural disasters through planning programs which have helped save lives in many natural disasters since Armero's tragedy.
In 1988, three years after the eruption, Stanley Williams of Louisiana State University stated that, "With the possible exception of Mount St. Helens in the state of Washington, no other volcano in the Western Hemisphere is being watched so elaborately" as Nevado del Ruiz. Communities living near the volcano have become wary of volcanic activity: when it erupted in 1989, more than 2,300 people living around it were evacuated.
Background
Armero, located 48 km (30 mi) from the Nevado del Ruiz volcano and 169 km (105 mi) from Colombia's capital of Bogotá, was the third largest town in Tolima Department, after the towns of Ibagué and Espinal. A prominent farming town before the eruption, it was responsible for roughly one-fifth of Colombia's rice production and for a large share of the cotton, sorghum, and coffee crops. Much of this prosperity can be attributed to Nevado del Ruiz, as the fertile volcanic soil stimulates agricultural growth.
Built on top of an alluvial fan that had been host to historic lahars, the town was previously destroyed by a volcanic eruption in 1595 and by mudflows in 1845. In the 1595 eruption, three distinct Plinian eruptions produced lahars that claimed the lives of 636 people. During the 1845 event, 1,000 people were killed by earthquake-generated mudflows near the Magdalena River.
Ruiz has undergone three distinct eruptive periods, the first beginning 1.8 million years ago. During the present period (beginning 11,000 years ago), it has erupted at least twelve times, producing ashfalls, pyroclastic flows, and lahars. The historically recorded eruptions have primarily involved a central vent eruption (in the caldera) followed by an explosive eruption, then the formation of lahars. Ruiz's earliest identified Holocene eruption was in about 6660 BC, and further eruptions occurred around 1245, 850, 200 BC, and in about 350, 675, in 1350, 1541 (perhaps), 1570, 1595, 1623, 1805, 1826, 1828 (perhaps), 1829, 1831, 1833 (perhaps), 1845, 1916, December 1984 through March 1985, 1987 through July 1991, and possibly in April 1994. Many of these eruptions involved a central vent eruption, a flank vent eruption, and a phreatic (steam) explosion. Ruiz is the second-most active volcano in Colombia after Galeras.
1985 activity
Precursor
In late 1984, geologists noticed that seismic activity had begun to increase in the area around Nevado del Ruiz. Increased fumarole activity, deposition of sulfur on the summit of the volcano, and phreatic eruptions also alerted geologists to the possibility of an eruption. Phreatic events, when rising magma encounters water, continued well into September 1985 (one major event took place on September 11, 1985), shooting steam high into the air. Activity began to decline in October, probably because the new magma had finished ascending into Ruiz's volcanic edifice.
An Italian volcanological mission analyzed gas samples from fumaroles along the Arenas crater floor and found them to be a mixture of carbon dioxide and sulfur dioxide, indicating a direct release of magma into the surface environment. Publishing a report for government officials on October 22, 1985, the scientists determined that the risk of lahars was unusually high. To prepare for the eruption, the report gave several simple preparedness techniques to local authorities. Another team gave the local officials seismographs, but no instructions on how to operate them.
Volcanic activity increased again in November 1985 as magma neared the surface. Increasing quantities of gases rich in sulfur dioxide and elemental sulfur began to appear in the volcano. The water content of the fumaroles' gases decreased, and water springs in the vicinity of Ruiz became enriched with magnesium, calcium, and potassium, which leached from the magma.
The thermodynamic equilibration temperatures, corresponding to the chemical composition of the discharged gases, ranged from 200 to 600 °C (400 to 1,100 °F); this is a measure of the temperature at which the gases equilibrated within the volcano. The extensive degassing of the magma caused pressure to build up inside the volcano in the space above the magma, which eventually resulted in the explosive eruption.
Preparation and attempted evacuation
In September 1985, as earthquakes and phreatic eruptions rocked the area, local officials began planning for an evacuation. In October, a hazard map was finalized for the area around Ruiz. This map highlighted the danger from falling material—including ash and volcanic rock—near Murillo, Santa Isabel, and Libano, as well as the threat of lahars in Mariquita, Guayabal, Chinchiná and Armero.
The map was poorly distributed to the people at high risk from Ruiz: many survivors had never heard of it, even though several of the country's major newspapers featured versions of the map. Henry Villegas of INGEOMINAS (Colombian Institute of Mining and Geology) stated that the hazard maps clearly demonstrated that Armero would be affected by lahars, but that the map "met with strong opposition from economic interests". He added that because the map was not prepared long before the eruption, mass production and distribution of it in time was difficult.
At least one of the hazard maps, published in the prominent El Espectador newspaper in Bogotá, included glaring errors. Without proper graphic scaling, it was unclear how big the map's hazard zones really were. The lahars on the map did not have a distinct ending point, and the main threat seemed to be from pyroclastic flows, not from mudflows. Though the map was colored blue, green, red, and yellow, there was no key to indicate what each color represented, and Armero was located in the green zone, wrongly interpreted to indicate the safest area. Another map published by the El Tiempo newspaper featured illustrations which "gave a perception of topography to the public unfamiliar with maps, allowing them to relate hazard zones to the landscape". In spite of this presentation that was keyed to the audience, the map ended up a more artistic representation of the risk than a purely scientific one.
The day of the eruption, black ash columns erupted from Ruiz at approximately 3:00 p.m. local time. The local civil defense director was promptly alerted to the situation. He contacted INGEOMINAS, which ruled that the area should be evacuated; he was then told to contact the civil defense directors in Bogotá and Tolima. Between 5:00–7:00 p.m., the ash stopped falling, and local officials, including the town priest, instructed people to "stay calm" and go inside. Around 5:00 p.m. an emergency committee meeting was called, and when it ended at 7:00 p.m., several members contacted the regional Red Cross over the intended evacuation efforts at Armero, Mariquita, and Honda.
The Ibagué Red Cross contacted Armero's officials and ordered an evacuation, which was not carried out because of electrical problems caused by a storm. The storm's heavy rain and constant thunder may have overpowered the noise of the volcano, and with no systematic warning efforts, the residents of Armero were completely unaware of the continuing activity at Ruiz. At 9:45 p.m., after the volcano had erupted, civil defense officials from Ibagué and Murillo tried to warn Armero's officials, but could not make contact. Later they overheard conversations between individual officials of Armero and others; a few heard the mayor of Armero speaking on a ham radio, saying "that he did not think there was much danger" just before he was overtaken by the lahar.
Eruption
At 9:09 p.m., on November 13, 1985, Nevado del Ruiz ejected dacitic tephra more than 30 km (20 mi) into the atmosphere. The total mass of the erupted material (including magma) was 35 million metric tons, only three percent of the amount that erupted from Mount St. Helens in 1980. The eruption reached 3 on the Volcanic Explosivity Index. The mass of the ejected sulfur dioxide was about 700,000 metric tons, or about two percent of the mass of the erupted solid material, making the eruption unusually sulfur rich.
The eruption produced pyroclastic flows that melted summit glaciers and snow, generating four thick lahars that raced down river valleys on the volcano's flanks, destroying a small lake that was observed in Arenas' crater several months before the eruption. Water in such volcanic lakes tends to be extremely salty, and may contain dissolved volcanic gases. The lake's hot, acidic water significantly accelerated the melting of the ice, an effect confirmed by the large amounts of sulfates and chlorides found in the lahar flow.
The lahars, formed of water, ice, pumice, and other rocks, incorporated clay from eroding soil as they traveled down the volcano's flanks. They ran down the volcano's sides at an average speed of 60 km/h (40 mph), dislodging rock and destroying vegetation. After descending thousands of meters down the side of the volcano, the lahars followed the six river valleys leading from the volcano, where they grew to almost four times their original volume. In the Gualí River, a lahar reached a maximum width of 50 m (160 ft).
Survivors in Armero described the night as "quiet". Volcanic ash had been falling throughout the day, but residents were informed it was nothing to worry about. Later in the afternoon, ash began falling again after a long period of quiet. Local radio stations reported that residents should remain calm and ignore the material. One survivor reported going to the fire department to be informed that the ash was "nothing".
During the night, the electrical power suddenly turned off and the radios went silent. Just before 11:30 p.m., a huge stream of water swept through Armero; it was powerful enough to flip cars and pick up people. A loud roar could be heard from the mountain, but the residents were panicked over what they believed to be a flood.
At 11:30 p.m., the first lahar hit, followed shortly by the others. One of the lahars virtually erased Armero; three-quarters of the town's 28,700 inhabitants were killed. Proceeding in three major waves, this lahar was 30 m (100 ft) deep, moved at 12 m/s (39 ft/s; 27 mph), and lasted ten to twenty minutes. Traveling at about 6 m/s (20 ft/s; 13 mph), the second lahar lasted thirty minutes and was followed by smaller pulses. A third major pulse brought the lahar's duration to roughly two hours. By that point, 85 percent of Armero was enveloped in mud. Survivors described people holding on to debris from their homes in attempts to stay above the mud. Buildings collapsed, crushing people and raining down debris.
The front of the lahar contained boulders and cobbles that would have crushed anyone in their path, while the slower parts were dotted by fine, sharp stones which caused lacerations. Mud moved into open wounds and other open body parts — the eyes, ears, and mouth — and placed pressure capable of inducing traumatic asphyxia in one or two minutes upon people buried in it. Martí and Ernst state in their work Volcanoes and the Environment that they believe that many who survived the lahars succumbed to their injuries as they were trapped, or contracted hypothermia, though the latter is unlikely, given that survivors described the water as warm.
Another lahar, which descended through the valley of the Chinchiná River, killed about 1,800 people and destroyed 400 homes in Chinchiná. In total, more than 23,000 people were killed, approximately 5,000 were injured, and 5,000 homes throughout thirteen villages were destroyed. Some 230,000 people were affected, 11,000 ha (27,000 acres) were disrupted, and there were nearly 20,000 survivor-refugees. The Armero tragedy, as the event came to be known, was the second-deadliest volcanic disaster of the 20th century, surpassed only by the 1902 eruption of Mount Pelée, and is the fourth-deadliest volcanic eruption recorded since 1500 AD. It is also the deadliest lahar, and Colombia's worst natural disaster.
Impact
The loss of life was exacerbated by the lack of an accurate timeframe for the eruption and the unwillingness of local authorities to take costly preventative measures without clear signs of imminent danger. Because its last substantial eruption had occurred 140 years earlier, it was difficult for many to accept the danger presented by the volcano; locals even called it the "Sleeping Lion".