Within Tanzania exists a volcano which is truly the world's strangest volcano. This volcano erupts
low temperature black lava which has a viscocity lower than water. This lava is highly enriched in
rare earth elements, and once it cools turns into a bright white rock. The volcano I am referring
to is Oldoinyo Lengai, which is the only volcano in the world to erupt this unique type of lava.
This video will discuss this volcano, and mention what its future hazards are.
The Oldoinyo Lengai volcano can be found in the northeast portion of Tanzania.
Specifically, it is 70 kilometers south of the border with Kenya, and northeast
of a series of geologically recent calderas. Like the majority of volcanoes in Eastern Africa,
this volcano exists due to the east Africa rift zone. In other words, the volcanic activity is
related to the slow process of the African tectonic plate breaking into two pieces
which are spreading apart from one another. The unique Oldoinyo Lengai volcano began around
370,000 years ago, when a series of explosive eruptions started to build a new volcano.
At one point, 353,000 years ago, a lake was present on the eastern side
of the volcano. However, an intrusion of magma caused this water to suddenly flash to steam
and explode. This explosive eruption created a 670 m volcanic crater known as a tuff ring.
By 338,000 years ago, the volcano was at least 500 meters tall. Over the next 300,000 years,
frequent explosive and effusive eruptions built the mountain to an elevation of around 3000
meters. These eruption caused the slopes of the volcano to become a steep 40 to 45 degrees.
Then, 10,000 years ago, a very large eruption took place. The lateral eruption caused 4.9
cubic kilometers of the volcano to suddenly slide off to the northeast,
in a manner quite similar to the 1980 eruption of Mount Saint Helens. This landslide moved a
thick layer of rock up to 24 kilometers north of the mountain. By the time the eruption had ended,
200 square kilometers was covered with an average thickness of 25 meters of rock.
8300 years later, a similar collapse occurred, but this time on the eastern slope of the mountain.
This collapse caused 200 million cubic meters of rock to slide up to 8.5 kilometers away.
The volcanic activity at Oldoinyo Lengai has been occurring at the same summit crater on
the south side of the mountain for more than 300,000 years. However, this summit crater has
since become extinct as volcanic activity shifted half a kilometer to the north.
This new crater erupted a very strange type of lava. Instead of being red or orange when
it erupts, it is solid black. A few days after it cools, it turned into a bright white rock
known as a carbonatite. During the last 10,000 years, more than 1500 volcanoes have erupted
on earth. This volcano is the only one to produce this unusual type of lava,
which can resemble snow from a distance. As an exploration geologist, I must stress
how fascinating and cool this lava is. Once the volcano is extinct, it could technically be
mined for rare earth elements, or other resources which it is enriched in such as barium, niobium,
and strontium. Simply put, mining companies around the world are currently searching for ancient
equivalents of this lava due to its high value. In the last 100 years, this volcano has erupted
16 times, including an eruption at the beginning of 2021. Although most of these eruptions are
primarily effusive, they can also be quite explosive. One of these larger explosive
eruptions occurred in 1966, and generated a pyroclastic flow which traveled several
kilometers. As a result, I would not recommend hiking the volcano while it is actively erupting.
However, the volcano poses a much greater danger as indicated by its two recent summit collapses.
These summit collapses occur with little warning, and can cause a landslide to reach more than
20 kilometers away. Another partial summit collapse is likely in the next 5,000 years,
which could fail in any direction. Until this next major eruption,
I would encourage tourists to visit this volcano due to its uniqueness and the
abundance of wildlife found nearby. I hope that you enjoyed this video.
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