Africa has many active volcanoes. Why was Nyiragongo the only one to make the Decade Volcano list?
Limits on funding and other resources in the 1990s forced volcanologists to choose carefully.
And Mount Nyiragongo, in what was then Zaire and is now the Democratic Republic of the Congo, was an outstanding candidate.
Unlike the other Decade Volcanoes, though, Nyiragongo has become even more threatening in the 21st century.
The International Decade (1990s)
Recent tragedies highlighted Nyiragongo’s threat to the region (which was getting more and more crowded despite its risks):
Two volcanic lakes elsewhere in Africa had “exploded” during the mid-1980s, releasing clouds of carbon dioxide that suffocated people and livestock in nearby villages.
Scientists knew that Lake Kivu, at the foot of Mount Nyiragongo, also has volcanic gases seeping in. And it’s much bigger than those two lakes and contains enough methane for Rwanda to tap as an energy source — as well as vast stores of carbon dioxide.
#Nyiragongo Volcano and #Goma City viewed from #Lake_Kivu on March 3, 2022, while sampling gases from deep waters of the Lake. #Monitoring_Lake_Kivu@VirungaSupersit @BuildWakanda243 @AsjRdc @ScienceRDC @AfriVolcaNet@Earthquakes_Rwa @Nyiragongoinfo @CoV11Crete @IAVCEI_official pic.twitter.com/5mYUxI99NA
— Charles Balagizi (@CharlesBalagizi) April 19, 2022
There is geologic evidence that lake overturns — the technical name for such explosions — have happened here before. (Balagizi et al.)
Two million people now live on Lake Kivu’s shores. Such an explosion — which could happen if the gas layers down there are disturbed by, say, lava erupting through the lake bed — would have truly biblical proportions.
Nyiragongo has hosted lava lakes in its summit crater for a long time, recorded perhaps as far back as 1894.
The Decade volcanologists knew that, on January 10, 1977, fissures had opened up, high on Nyiragongo’s flank, and the lava lake had drained out in less than an hour.
People — particularly children and the elderly — died in that eruption.
This volcano’s lava is extremely “runny.” When fresh from the depths (or lake) and very hot, it can easily beat Usain Bolt in a race down Nyiragongo’s steep slopes.
Casualty estimates vary, but Brown et al. report a probable toll of 50 to 100 lives in 1977.
Several villages were destroyed, too, and almost five square miles of farmland were lost.
How and why did this breach happen? Could it happen again? Decade Volcano experts needed to understand Nyiragongo much better.
Another thing that concerned them was the lack of volcano monitoring here.
As a concerned USGS team (Tuttle et al.) put it in 1990:
The variety of volcano-related hazards which threaten the inhabitants in the Lake Kivu area (lava flows, explosive phreatic eruptions, and volcanic heating and overturn of deep lake waters) make a basic monitoring system essential . . . To save lives in the event of a dangerous eruption, all residents must know what is expected of them if a warning is sounded: which way to run, how far, and how long to stay away. This will require a massive public education effort.
Unforunately, what the public got in the 1990s, instead of education, was genocide and military strife that claimed millions of lives and devastated the region.
During the International Decade, both Nyiragongo and its neighbor Nyamulagira erupted in 1994 while about a million refugees from the nearby Rwandan genocide were sheltering around Goma — the provincial capital located on Lake Kivu’s north shore and just 11 miles from Nyiragongo’s summit — on now-hardened 1977 lava flows.
In addition to the refugee camps, Goma’s 400,000 residents were also hosting crowds of rural Congolese villagers who had fled the fighting around their homes.
As it turned out, neither Nyiragongo nor Nyamulagira’s activity directly threatened any of these people, although indirect eruption effects on the environment as well as on international relief efforts were considerable.
Other long-term social ramifications of this crisis (ongoing civil unrest and militarism) are briefly mentioned near the end of this chapter.
All in all, this was not a good time to hold Decade Volcano workshops in Goma and field trips through disputed territory to Mount Nyiragongo.
Instead, various research efforts were made and locals and foreigners, working together, managed to establish a basic volcano observatory in Goma.
Despite many challenges since then for the observatory (some of them ongoing), this first little step in the 1990s toward monitoring Nyiragongo would pay dividends in coming decades that saw major eruptions in 2002 and 2021.
The 2002 eruption
According to the Global Volcanism Program (GVP) website bulletins, Nyiragongo’s lava lake didn’t come back for five years after it drained during the 1977 eruption.
It then quieted down in 1983 and stayed solid until fresh magma appeared 1994 — as mentioned, at the worst possible time for local people in crisis.
The reactivated lava lake did stay inside Nyiragongo’s summit crater and far below the level it had been at when the mountain cracked in 1977, draining the lake.
Now that Nyiragongo was a Decade Volcano, more resources were available, in addition to the new (but limited) Goma Volcano Observatory.
Scientists continued to watch the lake. In March 2001 it was still 120 meters below what they considered to be the “critical level.” (Global Volcanism Program)
Nevertheless, on the morning of January 17, 2002, part of the volcano’s south slope, at an elevation roughly two-thirds of a mile above Goma, opened up and the lava lake drained out of what quickly became a network of fissures.
Nyiragongo’s south flank also fractured a little farther down.
Each of these new cracks gaped a meter or more across, and lava erupted out of some of them.
This complex lower fissure system broke its way through the ground to Goma — six miles away — in less than eight hours.
In the afternoon, thick, sticky a’a lava erupted out of the southernmost fissure — the one closest to Goma — and slowly rolled through the eastern part of town.
This flow went on into Lake Kivu, but only down to a depth of about 260 feet (80 meters); per the Global Volcanism Program bulletins, the lake’s gas field starts about 660-980 feet (200-300 meters) down.
Like all of the East African Rift’s major lakes, Kivu is very deep.
So, in 2002 the lake didn’t explode, but ten to twenty minutes after that first flow into Goma began, a new fissure opened up nearby, west of the main system.
This a’a lava flow devastated a different part of Goma, but it did not reach the lake.
The resulting human catastrophe of 2002, summarized here, is beyond the scope of this chapter.
Human casualties were surprisingly low, all things considered. It isn’t easy to find definitive numbers, but probably between 70 and 147 people died in the 2002 eruption. (Global Volcanism Program)
Per United Nations figures, about 470 people were injured, 30,000 were displaced and 4,000 homes were lost, along with at least 13% of Goma’s infrastructure.
And according to this 2016 video, the 2002 eruption came while the Goma volcanologists’ dismissal papers were on the table.
They got in trouble for predicting the lava flows!
Since then, I have read, the first peaceful transition of power in the Congo since colonial days happened in the 2019 elections.
UN peacekeepers are also on duty here, and one of their tasks is to conduct public volcano emergency drills.
Those drills are absolutely necessary because Nyiragongo, oblivious to human affairs, keeps raising the stakes.
The 2021 eruption
Many of us remember the online coverage, like this, of Nyiragongo’s most recent major eruption.
On May 22, 2021, two or more fissures opened up on the south flank. At the same time, Nyiragongo’s lava lake (which had restarted in May 2002) once more drained.
The resulting rivers of liquid fire were over half a mile wide in some places. The lava eventually stopped just before reaching Goma International Airport.
At least 32 people died in this eruption, more than 20,000 were displaced, and some 3,600 homes, 12 schools, and 3 health facilities were destroyed. (Global Volcanism Program)
Seismicity from May 22 through May 24 showed events moving from Nyragongo’s summit area southward under Lake Kivu.
On May 25th, ground cracks that were a few tens of centimeters wide opened in various parts of Goma; per the GVP, some were hot and gassy, others showed flames.
One of these cracks was several hundred meters long and extended from the northern city limit toward the lake.
There was more bad news, too, but to understand that we need first to look briefly at Nyiragongo’s setting.
Nyiragongo and the East African Rift
Several hours after the 2002 eruption began, seismometers started showing an unusual number of tectonic quakes, some strong enough to register on equipment in China and Antarctica.
This was the south slope fissuring.
That it showed up isn’t surprising — seismometers are designed to detect ground breaking. But they also can show the difference between volcanic quakes and those due to the region’s tectonics.
Again, these 2002 quakes associated with Nyiragongo’s fissuring were tectonic.
Also, out in the field, experts had noted different eruption dynamics in the upper and lower fissure systems.
For those who knew how to interpret the data, these departures from what typically would be seen during an eruption raised an interesting question.
Was the energy that was breaking apart this massive fire mountain and the bedrock between it and Goma/Lake Kivu coming from Nyiragongo or from the much more powerful East African Rift?
You’ve probably heard of this rift, which is where Africa is splitting apart.
You might even be thinking of grassy rift valleys where cheetahs, lions, and other predators watch people (and vice versa):
Well, the East African Rift also contains deep lakes like Kivu and clusters of volcanoes wherever magma finds a way to rise through Earth’s fractured (rifted) crust.
Nyiragongo and its neighbors are part of the Virunga Volcanic Province (and also Virunga Volcanoes National Park) and sit in the western part of the great rift, just north of Kivu and not too far from Lake Victoria.
Those 2002 fissures on the volcano’s south flank line up with the African Rift in the area.
All of these points have led some volcanologists (mentioned in the April 2010 GVP bulletin) to suggest that Nyiragongo’s 2002 eruption was triggered by rift spreading rather than volcanic processes.
Now here comes the really bad news.
While some of Nyiragongo’s flank fissures appear to be under compression, all of those on the south flank fissures show very slow widening as well as temperature increases.
And a 2012 study mentioned by the GVP found a connection between a magnitude 6.2 earthquake that rocked the region eight months after the 2002 eruption and the formation of a 12½-mile-long underground magma channel (dike) between Nyiragongo and Lake Kivu.
Analyses during and after the 2021 eruption suggested that the lava flows came from the dike extending from Nyiragongo, under Goma, and likely underneath Lake Kivu.
— Adriano Nobile (@j_p_joule) May 26, 2021
INSAR doesn’t work on bodies of water, and it’s impossible to install instruments safely down there in the lake-bed gas field, so scientists can only say it probably extends under Lake Kivu.
As you’ll recall, eruption through the lake bed is something that could cause an explosive overturn, unleashing metric tons of carbon dioxide and methane on the lake’s hapless but numerous neighbors.
The lava lake returned in the fall of 2021 and is still active.
Unfortunately, civil unrest and fighting between the Congolese army and guerrillas in the area make volcano field work here hazardous.
Instruments are looted, so satellite monitoring is the main source of real-time monitoring.
On June 5, 2022, the Goma observatory reported (French) finding dead fish in one of Lake Kivu’s western bays and called for urgent scientific assessment.
Technically, there is nothing more the Decade Volcano program can do here. However, the knowledge base, data, technology, and most importantly, the human connections that grew out of that program over the last quarter century will all help the region deal with whatever Nyiragongo’s next move will be.
This is truly the world’s most dangerous active volcano.
June 11, 2022, statement by the UN Secretary General.
1.52° S, 29.25° E, North Kivu Province, Democratic Republic of the Congo. The GVP Volcano Number is 223030.
Per the Global Volcanism Program (GVP) website:
- Within 5 km (3 miles): 2,416.
- Within 10 km (6 miles): 31,145.
- Within 30 km (19 miles): 1,006,436.
- Within 100 km (62 miles): 9,087,529.
Orange. The lava lake was seen on June 6th Sentinel satellite imagery.
Biggest recorded event:
The city of Goma is built on the huge Buyinga lava flow. This happened 700-800 years ago and covers an area of almost 300 square miles.
The Goma Volcano Observatory. (French and some English)
Nyiragongo is in Toulouse VAAC’s area of responsibility.
Featured image: In this UN peacekeeper image from 2016, Virunga Park rangers contemplate Nyiragongo’s lava lake, while stars shine overhead. Balagizi et al. dedicated their paper to the rangers who have given their lives defending the park. (Image: MONUSCO, CC BY-SA 2.0)
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