Very few volcanoes on the planet contain an active long term lava lake.
A few examples of volcanoes which do include these rare summit features include Nyiragongo
in the Democratic Republic of Congo and Mount Erebus in Antarctica.
However, one volcano within Africa contains not one but two active lava lakes.
The volcano I am referring to is called Erta Ale, which is the most active volcano within
Ethiopia.
It has been continuously erupting since 1906, and is erupting right now.
This video will discuss this massive shield volcano, and mention what its future hazards
are.
The Erta Ale volcano can be found in northern Ethiopia, where it is just south of the border
with Eritrea.
This volcano is in a very geologically active area where the crust is slowly spreading apart
as the result of a divergent plate boundary.
As a result, the middle of this spreading area is far below sea level, from which lava
travels upwards and erupts onto a series of weak points in the crust represented by fissures.
These fissures are the site of several volcanoes, including Erta Ale, which is the largest in
this area referred to as the Danakil Depression.
Erta Ale is a massive shield volcano which towers to 613 meters above the surrounding
landscape.
It is approximately 50 kilometers or 31 miles wide, and is overlaid by several other active
volcanoes.
To prevent further confusion, I have outlined the boundaries of this massive volcanic complex,
which contain thousands of distinct lava flows.
It is not known when Erta Ale began to form, but the entire volcano is a minimum of 250,000
years old.
The initial eruption caused a large volume of lava to shoot several hundred meters into
the sky, thus creating a lava fountain.
Large quantities of lava then fell back to the ground, beginning the first river of lava
at this newly formed volcano.
As the eruptive sequence continued, a series of spatter cones were constructed in a chain.
Eventually, these vents merged until only two central vents remained.
Over the subsequent hundreds of thousands of years, numerous lava flows built on top
of each other out of a black rock type called basalt.
Basalt lava tends to have a low viscosity, allowing for it to travel long distances at
speeds of up to 15 kilometers per hour before it cools.
This allowed for the creation of a gentle sloped shield volcano which reflected the
fast speed of lava erupted from this volcanic complex.
Eventually, Erta Ale became too large to transport lava long distances, so during some eruptions
lava was forced underground.
This lava then reemerged at a more distant location in what is termed a flank eruption,
allowing for the volcano to continue building in size.
On occasion, a series of unusually large flank eruptions occur in rapid succession.
This drains a portion of the underlying magma chamber, causing the center of the volcano
to collapse downwards much like a sinkhole.
On Erta Ale, two of these features, called calderas can be observed.
Since at least 1906, the northern caldera has been continuously erupting.
Today, it contains two distinct lava lakes, one to the north, and one to the south.
Although Erta Ale is considered to be erupting right now due to the mere presence of two
lava lakes, this lava is not largely moving anywhere.
In the event that the lava was to erupt outside of these lakes, several hazards would be created.
The most likely scenario for a future eruption is that the lava overflows one or both of
the lakes, and flows into sections of the small caldera rim.
Eventually, part of the caldera rim would overflow, causing a lava flow to travel downhill.
However, since Erta Ale contains a network of lava tubes, an eruption could technically
occur anywhere on its edifice with little warning, including on its edge.
These distant flank eruptions are largely responsible for the large volume events which
create up to 25 kilometer long lava flows.
Additionally, whenever an eruption occurs, it will eject bombs of lava in a several hundred
meter radius through spatter cones and fissures.
With this being said, the most dangerous hazard at Erta Ale are the levels of carbon dioxide
it emits.
Since the volcano occurs in a natural valley, this carbon dioxide pools in low points which
can lead to lethal concentrations.
Be careful if you ever decide to visit this beautiful volcano.
I hope that you enjoyed this video!
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