In terms of volcanic hazards, you might be surprised to learn that the danger
lava flows pose is quite low. Lava generally moves quite slowly, typically less than a kilometer per
hour. As an example, the lava from the current eruption at La Soufriere on the island of Saint
Vincent is moving at about 8 meters each day. However, there exists a volcano in Congo which
breaks the norm with its ridiculously fast lava flows. During two previous eruptions,
lava from Mount Nyiragongo has been recorded traveling at more than 100 kilometers or
60 miles per hour. This video will discuss this volcano, explain why its lava moves so quickly,
and mention what its future hazards are. The Nyiragongo volcano can be found in
the central portion of Africa within the democratic republic of Congo. Specifically,
it can be found 10 kilometers west of the border with Rwanda, and is 16 kilometers north of Goma.
Despite how well studied recent eruptions from this volcano are,
we don't actually know what happened at this volcano before 1884. As a result, the information
I am about to present is merely an educated guess based on the limited data available.
Mount Nyiragongo is built in-between two older stratovolcanoes, Shaheru and Baruta. Shaheru
likely formed through explosive basaltic eruptions about 250,000 years ago, while Baruta formed about
200,000 years ago. After these two stratovolcanoes went extinct, a large north to south trending
fault opened through a large earthquake. This allowed magma to once again reach the surface
around 175,000 years ago. Over tens of thousands of years, lava largely erupted out of Nyiragongo
in an effusive manner. This lava had the lowest silica content seen at any volcano on the planet.
The less silica lava has, the faster it moves. As a result, flows of lava often traveled
downslope during eruptions at more than 100 kilometers per hour. This gave the volcano a broad
profile similar to a shield volcano. Then, 30,000 years ago, the profile of the volcano changed.
Eruptions suddenly became far more explosive, and emitted lots of ash in vulcanian style eruptions.
On occasion, short distance pyroclastic flows would travel a few kilometers down the mountain.
During this period of eruptions, the steep final 500 meters of elevation on this volcano was built.
Since then, eruptions have once again become largely effusive in nature.
Beginning in 1927, a large active lava lake slowly built up at the summit crater. For
the next 50 years, this lava creeped higher and higher. Then, on January 10th, 1977, the summit
lava lake rapidly drained away. Within minutes, lava that was traveling underwound burst out onto
the surface 4 kilometers to the south. From this vent and a related fissure emerged a river of lava
which traveled reportedly at speeds of up to 100 kilometers per hour. The lava moved so quickly,
that as it traveled through the forest, it did not set fire to trees or vegetation. As the lava
raced downwards, it eventually reached the edge of a densely populated city, Goma. In the next
several minutes, tens of thousands of structures were destroyed by this lava flow. Luckily,
the eruption of 22 million cubic meters of lava stopped short of the most densely populated
portions of the city. However, this would not be the case for the next outburst of lava.
In 2002, the lava lake once again rapidly drained from the volcano. Within minutes,
25 million cubic meters of lava burst out from 6 vents along a largely hidden fault.
Three of these flows ran straight through Goma. One of these covered the northern
third of the international airport with lava after which is flowed straight into Lake Kivu.
Many lives were lost, and more than 100,000 people were left homeless.
Today, in 2021, the volcano once again contains a large lava lake which has been slowly expanding
since 2002. This could catastrophically drain once again with only a minute's notice,
causing additional destruction. One suggestion I have in how to mitigate this threat is to build
walls of dirt and rock which will direct these future flows of lava into a central point. In
this central point, a meter deep trench should be dug which extends to Lake Kivu. (pause 2 seconds)
I have an additional hazard to note. All around the slopes of the volcano, including
in downtown Goma are a series of fumaroles. Do not, under any circumstances build near these,
or in a natural lowpoint nearby. Fumaroles emit high amounts of toxic gas which are
heavier than air and pool in low points. I hope that you enjoyed this video.
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