Armero Tragedy

The Nevado del Ruiz is an ice-capped stratovolcano in the central ranges of the Andes Mountains. It is part of the Pacific Ring of Fire and was formed by the Nazca Plate subducting underneath the South American Plate (Huggel et al). The volcano is apart of the Cordillera Central, the highest region of the Andes within Columbia, along with five other similarly ice-capped volcanos that make up the highest peaks in Columbia. In 1985, Nevado del Ruiz erupted, producing massive lahars that destroyed the nearby town of Armero and damaged Chinchiná killing roughly 23,000 people (Driedger et al 2020). This event was termed the Armero tragedy and is the second-deadliest volcanic-caused catastrophe of the 20th century.

Historical Components - Duncan McLendon

Nevado del Ruiz is the second most active volcano in Columbia and has been consistently erupting for 1.8 million years (Huggel et al). Prior to its 1985 eruption, its last most significant eruptions were in 1595 and 1845, killing roughly 600 and 1000 people respectively (Driedger et al 2020). In the 1595 and 1845 eruptions, the settlement in what is today's Armero was buried by mudflows from the volcano. The history of these prior disasters was forgotten as the town was rebuilt for the third time in the same location (The Eruption of Nevado Del Ruiz Volcano Colombia 10). By 1985, with a substantial increase in population as compared to the 1845 eruption, Armero was simply a disaster waiting to happen. The two towns most affected were Chinchiná and Armero, both built inside valleys that had served as natural run-offs for lahars and mudflows created by the volcano.

Exactly a year before the 1985 eruption, a number of low intensity earthquakes heightened local awareness of the possibility of an eventual eruption (The Eruption of Nevado Del Ruiz Volcano Colombia 11). Throughout September and October 1985, a series of geological surveys of the volcano's activity found a significantly increased threat of lahars (Barberi). This increased risk encouraged local authorities to begin preparedness planning and publish a risk map similar to the one imaged below (The Eruption of Nevado Del Ruiz Volcano Colombia 51-52).

In addition to hazard maps, local at-risk towns received thousands of flyers and pamphlets, like the one seen below, that detailed the risks, warning signs, and appropriate responses to eruptions (The Eruption of Nevado Del Ruiz Volcano Colombia 55). However, some towns, such as Armero, were simply not prepared in the event of an eruption. Many government officials did not take the possibility of risk seriously and worried that informing the people would cause unnecessary panic and strife (The Eruption of Nevado Del Ruiz Volcano Colombia 57).

Events - Abby West

Nevado del Ruiz is a large stratovolcano (made of layers of lava, ash, and pyroclastic deposits) located northwest of Bogota, Colombia. It is closest to the South American-Nazca Plate meeting where there is a subduction zone. The Arenas crater sits at the top of the volcano, along with glaciers.

The volcano had some activity in September of 1985 with some ash ejection and slight earthquakes near the end of the month and into October. In November the seismic activity started to pick up with more swarms of earthquakes, which indicated magma buildup (McClelland). On November 13th there was an initial eruption which resulted in primary effects such as a thin layer of ash fall and tephra being blasted from the volcano. The secondary effects of the eruption was what made it so incredibly deadly. The heat of the volcano melted the icecaps, which lead to very intense lahars all the way down to the surrounding towns. The town of Armero was hit the hardest and in total this eruption resulted in around 25,000 deaths. Armero can be seen in the path of the mudflow in Figure 2.

The response of the people living in the area was slow as they did not view evacuation as urgent. Some residents stayed inside as instructed to avoid the ashfall not knowing they would be buried by the 30-meter-high mudflow. In one story, they were told to just admire the beauty because it was a once in a lifetime opportunity (Florez and Garzon). Many families also continued on with their daily lives due to the lack of warning; “there were no reports that systematic efforts to warn large numbers of Armero residents had actually taken place” (National Research Council). The effects of the lahars in the town of Armero can be seen in Figure 3.

Post-event context - Amanda Bishop

After the eruption, the first lahar entered Armero at 11:30 PM. Seismologists concluded that the area was at a high risk for lahars, and expected preventative measures to be taken, even though they weren’t (Augliere, 2016). 

After the disaster, international aid allowed Colombian volcanology to grow considerably aided in establishing a system of observatories. Additionally, locals were given 14 different hazard maps for their region that were produced for the authorities (Garzón & Flórez, 2022). The volcano continued to have minor eruptions throughout November of 1985 (Pierson, 1985). While a tragedy should not have been necessary to establish a better safety system for the Colombians, the Armero tragedy gave the Colombians the resources they needed to better understand the threats of volcanos and the benefits of evacuation and preventative measures (Garzón & Flórez, 2022). These initiatives have proven to be invaluable. In June of 1989, the volcano had a similar eruption to the one that devastated the town of Armero. However, when a new monitoring station picked up extra seismic activity, warnings and daily updates on the volcano were posted. This led to the eruption resulting in zero human deaths (Garzón & Flórez, 2022). 

An hour after a twenty-minute-long eruption that spewed out magma, a lahar reached the nearest town to the volcano - Chinchiná. In Chinchiná, around a thousand individuals were killed and 200 homes were destroyed, as well as 3 bridges (Augliere, 2016). Multiple lahars entered Armero around 11:30 PM, killing over twenty thousand of the original twenty-nine thousand occupants. Five thousand individuals were injured by the lahars, and over seven thousand were left homeless throughout the region. The lahars devastated the local area by destroying roads, farmer’s fields, bridges, telephone lines, and aqueducts. Collectively, the multiple lahars destroyed two hospitals, fifty schools, and over five thousand homes. The area lost thirty percent of rice and grain crops, around half a million bags of locally produced coffee, and sixty percent of its livestock (Augliere, 2016). 

Summary/Outlook/Forecast

Duncan McLendon, Abby West, and Amanda Bishop

In the immediate aftermath of the catastrophe, a total of twenty-six countries provided relief and support for the assistance and recovery of the victims. By the end of the first week following the eruption, roughly $2,330,00 was donated by the U.S., Japan, Iceland, and France, as well as hundreds and thousands of helicopters, tents, blankets, and necessities that came from nearby countries (Osterlund). In the months that followed, the Columbian government came under fire for its inadequacy and irresponsibility in handling the warnings and crisis of the tragedy. In response, the government established the National Office for Disaster Preparedness to support similarly at-risk towns. Over the years, increased governmental responses have resulted in community education programs, volcano hazard assessments, volcanic activity monitoring, and even the creation of a unique threat level warning system for volcanic eruptions, pictured below (Driedger et al 2020).

The Nevado del Ruiz volcano has most recently erupted in December of 2022, with gas-and-ash emissions and rock fracturing (Smithsonian Institution, 2023).  According to the Smithsonian Institution, it is considered to be in a state of eruption from December 19 ^th  to the current date. Luckily, the Columbians have much better warning and preventative systems in place for volcanos following the Armero tragedy in 1985 (Garzón & Flórez, 2022). While the current eruptions would be considered minor, the Nevado del Ruiz volcano has had major eruptions since as early as 6660 BC. This volcano is located along the Nazca plate, which likely explains why it has been so eruptive in the past and why it will likely continue to erupt for centuries or millenia to come (Smithsonian Institution, 2023).