The nation of Tanzania in Africa contains a number of interesting and unusual volcanoes.
For example, Ol Doingo Lengai, which erupts black water like lava which then crystallizes
as a white color.
Or, Mount Meru, which has an impressive crescent shaped caldera in its eastern side.
However, neither of these are as old or large as a volcano which contains the highest point
in Africa.
The volcano I am referring to is Mount Kilimanjaro which is 100 kilometers long and 65 kilometers
wide.
Although this volcano could be best classified as dormant, there is active magma present
only 400 meters beneath its summit.
As such, it could only be a matter of time before this volcano erupts once again.
This video will discuss this fascinating volcano, and mention what its future hazards are.
Mount Kilimanjaro is located in northeast Tanzania, where part of its volcanic complex
straddles the border with Kenya.
Despite common belief, Kilimanjaro is not actually a shield volcano.
Despite its massive size, Kilimanjaro is in fact best classified as a stratovolcano.
If you look at Kilimanjaro from an angle, you can see that the volcano has three distinct
regional high points.
These high points are all individual volcanic cones, which are nested on top of one another.
These cones are all oriented in an east-southeast direction, which represents a regional weak
spot in the crust.
The westernmost volcanic cone is known as Shira, and was the first to begin forming
when it began erupting 2.5 million years ago.
The eruptions which occurred at Shira could best be compared to those at Mount Fuji.
Its eruptions were moderately explosive, and the lava which built this cone had the composition
of basalt.
As a result, the slopes of this volcanic cone grew to be gentler than most stratovolcanoes,
averaging around 10 degrees.
By 1.9 million years ago, Shira had grown to an impressive height of 4500 meters.
Then, during the waning lifespan of this cone, a large volume of lava erupted at once on
the flanks of the volcano.
This drained the underlying magma chamber, causing it to collapse and form a large caldera.
The creation of this caldera caused the cone to lose about 800 meters in height.
For the next 900,000 years, no additional eruptions occurred.
Then, 1 million years ago, a new volcanic cone emerged from the ground 16 kilometers
to the east of Shira.
This cone, known as Kibo, subsequently started erupting in a similarly explosive manner to
the previous cone.
After 50,000 years of eruptions, a third volcanic cone to the east began to concurrently erupt
with Kibo.
Eventually, this cone which was called Mawenzi, became the dominant of the two active vents.
Over the subsequent period of several hundred thousand years, erupted material from these
two cones piled on top of one another, forming a very tall volcanic complex.
Then, 448,000 years ago, Mawenzi erupted for the last time.
As explosive eruptions at Kibo continued, it eventually became tall enough that a permanent
glacier began forming on its summit.
As a result, many subsequent eruptions melted a portion of these glaciers, generating mudflows
referred to as lahars.
By 200,000 years ago, Kibo was 6400 meters tall.
However, at depth, magma began flowing to the east and west along a regional weak point
in the crust.
This severely drained Kibo's magma chamber, causing the volcano to collapse and lose 500
meters in elevation.
Over the next several thousand years, the remaining lava erupted on the flanks of the
volcano, forming more than 200 small cinder cones and tuff rings.
Since 150,000 years ago, no additional eruptions have occurred.
Today, Kilimanjaro stands at 5,881 meters in height.
Although it has not erupted in a long time, the summit of Kibo occasionally contains a
series of active fumaroles which vent volcanic gas, hinting at magma not far beneath the
surface.
As such, the odds of Kilimanjaro erupting anytime soon are relatively low, at about
1 in 50,000 each year.
Kilimanjaro will erupt again, but it will likely be a long time before it does.
When Kilimanjaro does erupt again, its main threat would be long distance lava flows which
could travel more than 30 kilometers from an erupting vent.
I hope that you enjoyed this video.
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