When people who live within Africa think of the most active volcano on the continent,
they often think of two volcanoes.
They either think of the Erta Ale shield volcano in Ethiopia, or the Nyiragongo volcano in
the Democratic Republic of Congo.
However, neither of these volcanoes are the most active on the continent.
The title for the most active volcano is a shield volcano called Nyamuragira.
This volcano is more than 3000 meters tall, and is erupting right now.
This video will discuss this volcano, and mention what its future hazards are.
The Nyamuragira volcano is located in central Africa in the Democratic Republic of Congo.
Specifically, it is located 13 kilometers to the north-northwest of its neighboring
stratovolcano, Nyiragongo.
However, unlike Nyiragongo, this volcano has never produced highly explosive eruptions.
As a result, despite containing essentially the same composition as its neighboring volcano,
it does not have a steep slope.
Rather, it has a gentle slope, which is typical for a shield volcano.
Currently, scientists are not exactly sure how old this volcano is.
However, I have made a minimum age estimate based on the volume of lava this volcano has
erupted in recorded history.
If the eruptive volume has consistently stayed the same, it meant that Nyamuragira is at
least 20,000 years old.
Today, its large edifice is 25 kilometers wide, and contains a volume of 500 cubic kilometers
of volcanic rock.
This impressive shield volcano towers to 1500 meters above the surrounding landscape.
The most prominent feature of Nyamuragira, is a 2 x 2.3 kilometer wide caldera which
surrounds the volcano's summit.
Contrary to common belief, this caldera was NOT formed through a highly explosive eruption.
Rather, it formed in a similar process to the expansion of the caldera at Kilauea in
2018.
There, a large volume flank eruption occurred, draining the overall volcano's magma chamber.
This caused the overlying caldera to collapse downwards, thus filling the empty space.
Just like Kilauea's caldera, it has multiple layers, representing several successive collapse
events.
These events have not been dated, but likely occurred over a span of several thousand years.
In the southeastern crater wall, a prominent fissure is visible in the ground.
This fissure represents a zone of weakness in the crust, which trends all the way to
Nyiragongo.
These fissures are the site of the vast majority of eruptions from Nyamuragira, which is why
its lava flows generally initially head in a southeast or northwest direction.
Although most of these flank lava flows don't travel very far, one notable flow traveled
34 kilometers away to the north, indicating a long duration and highly fluid flow.
Speaking of lava flows, both Nyiragongo and Nyamuragira contain unusually low silica lava,
resulting in fast lava flows.
However, the lavas from Nyiragongo contain 36.7% silica whereas the lavas from Nyamuragira
contain 44.8% silica.
However, there is a second link between these two volcanoes.
After major eruptions at Nyiragongo, Nyamuragira immediately has a drop in eruptive intensity.
Although this is purely speculative, these two volcanoes likely share a joint magma chamber
at depth.
The recent eruptions from Nyamuragira are quite numerous, and have covered dozens of
square kilometers.
Just so you can understand how quickly everything gets vegetated, the lava flow I have outlined
on screen formed from the Muhara cinder cone in 1976 to 1977.
Everything which shows up as a black or gray outline on satellite is younger, forming in
the last 40 years.
In terms of overall hazards, Nyamuragira is still a dangerous shield volcano.
The main threats from this volcano are due to lava flows, and moderate volumes of ashfall
from cinder cone forming eruptions.
A flank eruption could technically occur within a vast 1800 square kilometer area, even in
Lake Kivu.
The vent being shown on screen is within Kivu, and formed when magma at depth caused lake
water to flash to steam and explode, thus creating a tuff ring.
Several other tuff rings can be found in the area, suggesting the potential for future
explosive eruptions and associated short distance pyroclastic flows.
With all of this being said, the main threats are to four cities which I have outlined on
screen.
These cities are either built on top of or adjacent to recent lava flows from this volcano.
As such, it may only be a matter of time before a flow of lava overruns one of these cities.
I hope that you enjoyed this video!
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