This is one of the geological wonders of
the world.
The Great Rift Valley.
A breathtaking 6,500 km depression in
Africa which has the East African Rift
at its heart. It is so vast it's visible
even from space.
On the surface, it truly is one of the
most remarkable beauty spots on Earth.
But the area hides a sinister secret
deep below.
This peaceful looking paradise is
actually one of the most violently
active tectonic faults on Earth.
Beneath the feet of 120 million people,
a colossal force is pulling at the very
foundation of a continent.
For more than 20 million years, a giant
crack has been spreading down the east
side of Africa, cutting through
Ethiopia, Kenya, and Tanzania,
slowly but surely, ripping Africa in
two. I'm James Stewart, and you're
watching Astramm Earth. In this video,
we'll explore the forces of nature
behind this geological powerhouse. ask
whether the second largest continent in
the world really is tearing itself
apart. And if so, what does that mean
for Africa?
What kinds of consequences can we expect
from the biggest continental reshaping
event since the breakup of Pangia?
If you were to peer into the Earth's
crust in this part of the world, you'd
find the African plate, which boasts the
fourth largest tectonic boundary in the
world. And that's just the major one.
The African plate is further split into
the Nubian plate to the west, which
carries most of the African continent,
and the smaller Somali plate to the
east, which carries the Horn of Africa,
the easternmost extension of African
land.
But this was not always the case. Until
recently, geologists thought there was
only one plate in Africa.
It wasn't until the 1970s that Kevin
Burke and John F. Jweyey provided
compelling evidence that the single
plate model didn't fit and that the
African plate had actually been
separating as far back as the Cretaceous
period. These two plates pulling apart
is what creates the East African rift
system. The more technical term for this
battleground is a divergent plate
boundary as the Somalian tectonic plate
and the larger Nubian tectonic plate
move away from each other.
To make matters worse, the Nubian and
Somalian plates are also separating from
the Arabian plate to the north. This has
created a Y-shaped rifting system in the
Afar region of Ethiopia known as a
triple junction. Further adding to
concerns a split may be inevitable.
Central to the movement of these
tectonic plates is the Earth's
lithosphere, the layer of solid rock
that makes up the lands that we walk on
and the ocean floors we see today. As
impressive as it sounds, it's very thin
and often compared relative to the skin
of an apple. The lithosphere floats on
top of the mantle, a layer of semi-olid
rock that behaves like a thick, slow
flowing liquid. Heated by the core of
our planet, which is as hot as the
surface of the sun, the semiolid rock
rises toward the lithosphere, where it
then flows outwards, cools, and sinks
back down again.
These thermal currents drag the
continents around the surface of the
planet in a process called continental
drift. We have a whole video on lost
continents if you want more on this. To
keep things brief here, this was one of
the main drivers behind the ancient
superc continent Gondana breaking up 180
million years ago and splitting into the
land masses we recognize today. Africa,
South America, Australia, Antarctica,
the Indian subcontinent, and the Arabian
Peninsula. There is still some debate
about whether Africa will split apart or
not, but the leading theory as to how
this could happen centers around an
underlying superheated plume. In this
animation by our friends at Fern, you
can see how the thermal current in the
lithosphere, heated by the Earth's core,
rose towards the surface, lifted and
eventually cracked the superc continent.
It then quite literally dragged Africa
and South America apart, relieving the
pressure that had built up and allowing
gravity to pull the two pieces back down
and forming what is now the Atlantic
Ocean.
A similar process far more recently
formed the Red Sea at the northern end
of the East African rift system.
It was a geologically unstable valley
surrounded by high mountains pushed
upwards from below until it reached
breaking point. The valley above the
fault gradually thinned and became
weaker the more it was stretched. As the
Arabian plate below separated from the
Nubian plate, the stretched lithosphere
above collapsed and gradually opened the
Gulf of Aiden and eventually the Red
Sea. Discussions are ongoing as to
whether the same thing is happening here
in Africa, with the main hypothesis
suggesting that rising thermal plumes
within the Earth's mantle are causing an
upward bulge and stretching of the
lithosphere comprising the crust and
upper mantle beneath Kenya and Ethiopia.
This lithospheric thinning has resulted
in extensive outpouring of bassalt lava
characterized by lava flows erupting
from newly formed fishes. fracturing the
brittle continental crust into a system
of faults.
In short, planet Earth, and indeed this
region specifically, has a history of
splitting apart. So, you can see why
this concern would stand to reason. So,
what would happen if it did split?
Today, the rift remains above sea level,
but if it continues to widen, the land
within the valley will sink. Now
eventually this would allow water from
the Indian Ocean to flood into the basin
creating a sixth ocean.
Ken Macdonald a marine geoysicist and
professor at the University of
California said eventually this area
would become its own small continent.
The very makeup of planet earth would
look significantly different. The
traditional shape of Africa that we all
know would be almost unrecognizable.
The future version of Google Maps,
whatever that may be, would exhibit a
large island with a new continent
plonked in the Indian Ocean consisting
of parts of Ethiopia, Somalia, Kenya,
and Tanzania. This transformation could
affect quite literally everything from
biodiversity to water resources and
agricultural practices. Moreover, the
gradual separation might influence the
continent's geopolitical landscape, too,
as new maritime routes emerge and
nations reassess their territorial
boundaries.
But how quickly could that happen? Well,
at present, GPS measurements indicate
that the Nubian and Somali plates are
pulling apart from one another at an
average rate of 7 mm per year, although
estimates vary.
for the Somali plates to completely
break away and form a new ocean. Then it
would likely take tens of millions of
years. At that level, who's to say who
might be around to feel the effects or
see what the planet may look like? As
daunting a prospect as it sounds, there
may be some upsides, too. And one in
particular is something the world is
currently crying out for.
The main benefit of having an enormous
upswelling of magma beneath your feet is
access to a rich resource of geothermal
energy. If it became more easily
available, it could make several
countries above this fault completely
self-sufficient energy-wise. Ethiopia
and Kenya have already reached a
geothermal power generation capacity of
over,00 megawatt. And you'd imagine this
number would multiply significantly.
With the world actively looking for
renewable energy resources to replace
the burning of fossil fuels, the
countries that span the East African
Rift system could be sitting on an
economic gold mine. Whilst there is
still some debate about whether this
will or won't happen, there has been
some compelling evidence to back up the
will argument. In September 2005, a huge
crack did appear in Ethiopia's Afar
region. seemingly overnight. Despite
quite obviously looking like it should
have been created by the fault opening,
that doesn't appear to be the case.
Instead, the crack opened when a volcano
at the northern end of the rift called
Dabahoo erupted.
The Fisher exploded out of the side of
the Dabahoo volcano, which had been
inactive in recorded history.
The Dabahoo volcano began to swell,
followed by a swarm of 131 earthquakes.
Then, on the 26th of September, 2005, an
eruption blew out a vent of boulders and
ash, leaving a crater 500 m long and 100
m wide.
Using sensor data, a team of researchers
at Adis Ababa University in Ethiopia
found that a 60 km long, 8 m wide dyke
of solidified magma formed in the rift,
causing the crack in a matter of days.
Okay, that explains that crack. But
there was also one in 2018. This time in
Kenya, where a 1 km chasm opened up
seemingly out of nowhere. Surely this is
evidence enough of continental rift.
Well, maybe. But it seems like the
answer is actually much much less
dramatic.
While the larger rifting system could be
the underlying mechanism for the chasm,
the sudden appearance was likely due to
heavy rainfall in the area. The general
consensus among geologists now is that
the pre-existing crevice had remained
undetected because it was packed with
volcanic ash from eruptions in the
distant past. It was then suddenly
exposed when the deep layers of ash
collapsed and were washed away, leaving
behind a giant scar in the ground.
So it seems like Africa might not be
splitting apart after all. And surely a
continent not being ripped apart is good
news, right? Well, in this case, I'm
afraid not.
You know what's got more cracks than an
entire continent? My internet browsing
history. Honestly, surfing the internet
today is like trekking through the
Sahara with no sunscreen. Dangerous,
unpredictable, and full of shady things.
Even more annoyingly, for a channel that
quite literally covers the entire world,
you wouldn't believe how many sites,
videos, and papers are more landlocked
than this entire continent. That's why I
use NordVPN. As well as being my online
bodyguard, it also lets me access papers
and articles from all around the world
by changing my location so we can bring
you the very latest in scientific
developments. Nothing falls through the
cracks either. Nord's dark web monitor
alerts me before hackers plunder my
accounts. And even when working remotely
across the dodgy free Wi-Fi cafes of
Europe, NordVPN keeps my data locked up
tighter than the Panama Canal. You know
how it is. You see a deal online. Laptop
for five bucks. Yeah. Okay. And I've got
a beachfront property on Mars. Nord's
threat protection pro spots fishing
sites before you click. It's like having
Google Maps for these sketchy alleys of
the internet. So, why not check it out?
You can get NordVPN's 2-year plan plus 4
months extra. Really great deal at
nordvpn.com/astramar.
It's risk-free with Nord's 30-day money
back guarantee as well. Great deal. The
link is in the video description and on
screen for you right now as we head back
to the video.
In fact, Africa splitting apart might
actually be the lesser of two evils. Let
me explain. You see, it is also possible
that the geological forces driving the
rifting might prove too slow to
eventually separate the Somalian and
Nubian plates.
Cynthia Ebinger, chair of geology at
Tulain University in New Orleans and a
science adviser to the United States,
points out that failed rifts mark
continental land masses worldwide.
She draws attention to the mid-continent
rift in the very heart of North America,
which curves for about 3,000 km across
the upper Midwest.
Just over a billion years ago, the
mid-continent rift system was once a
similar divergent rift fault, a 3,000 km
long feature ready to split what is now
North America into three pieces.
It was powerful enough to create Lake
Superior. And the enormous crack through
the Earth's surface spread as far
southwest as Kansas. And then nothing.
It just stalled. fell silent, a
continent killer vanishing into the
darkness.
Over time, it has completely solidified
and is now one of our best examples of a
failed rift system.
One of the most noticeable features of
the mid-continent rift system are its
vast deposits of bassalt, an ignous rock
formed from huge outpourings of lava,
working almost like a geological glue.
This bassalt has helped to heal the
rifting fault, holding it together for a
billion years like Earth's self-healing
bandages.
The scale of this is difficult to
absorb. Those lava flows spread from
Lake Superior across six American
states. But why did this happen? And
could it be a clue as to what's
happening underneath Africa as we speak?
As we talked about earlier, continental
rifting occurs when magma below the
surface is forced upwards and rips open
the lithosphere. And this is what failed
to happen in the American mid-continent
rift system.
The crack through the Earth's crust
could not open for some reason that we
do not yet understand. So instead of
slowly pushing the fault apart, the
magma under enormous pressure from below
burst through the cracks and flowed out
onto the surface.
It's been estimated that more than 2
billion cub km of lava erupted through
the mid-continent rift with individual
flows exceeding 600 c km extending more
than 40 km across.
Staggeringly, this was only one single
eruption. And there were many eruptions,
hundreds of thousands of eruptions
combining to form continuous lava flows.
The area they covered was enormous, and
they would have obliterated everything
in their way.
So if we apply that same event to
Africa, if the East African rift system
cannot spread sideways, that enormous
pressure will have nowhere else to go
but up.
So actually, are those cracks the early
warning signs of something much worse
than a continent splitting? Are we
looking at a failed rift which would
create a disaster of global proportions?
Before we get stuck into this, I do want
to point out that while there are a lot
of similarities between what happened a
billion years ago in North America and
the East African rift system, there are
also some differences. So any
predictions are just that, predictions.
Much like a paleontologist piecing
evidence together to envisionage the
creatures that once walked our planet,
we can use the North American example to
help create a well-informed potential
scenario in Africa.
Because we can't see what's happening
below the magma layer, our knowledge
comes from the analysis of lava flows
that erupt at the surface and from
methods like seismology that can
construct a picture of what's happening
inside our planet from the way
vibrations travel through it. From this
information and making comparisons with
ancient rock formations, scientists can
build models that best explain what they
believe is happening beneath us. But we
can't dig a hole and go down to find out
how accurate these models are. Now, what
these geological models indicate is that
there is a super plume of hot magma
rising underneath the East African rift
system. As we've discussed, and
incidentally, the same conditions
prevail that existed at the early stages
of the mid-continent rift system. No two
faults are ever exactly the same, but it
does raise the possibility that instead
of Africa splitting apart, that magma
plume could cause lava to flow out onto
the surface and the results of that
happening would be catastrophic.
If the East African rift system behaves
in a similar way to the mid-continent
rift system, what we can expect are
eusive eruptions. Those are less violent
but involve much more lava. The sort of
lava flows to the ones we saw in North
America would cover nearly half of
Ethiopia, most of Kenya, and even extend
into Uganda and Tanzania. Here's where
it gets really scary, though, because
the East African rift system is not on
the same scale as the mid-continent
rift. It's three times bigger.
There have been no ausive eruptions in
human history that even compare to the
size and scale of this. The eruption
that comes closest and was the biggest
in recent history was in Lackey,
Iceland, which started in 1783 and
lasted 8 months.
The haze caused by this eruption reached
as far as Syria, caused crop failures,
killed off much of Iceland's livestock,
and sadly a quarter of the population
perished from the resulting famine.
For comparison, this was from an
eruption of a mere 14 km of lava. just
one single lava flow from the
mid-continent rift exceeded 600 cubic
km.
In other words, if the East African rift
system does follow the pattern of the
mid-continent failed rift with large
eusive eruptions, the consequences will
be severe.
Remember this area is the largest
seismically active rift system in the
world.
The Dabahoo volcano in the Afar Triangle
began to swell in 2005.
There are 78 active volcanoes in the
East African rift system. Monitoring of
previously dormant volcanoes within this
rift system between 2003 and 2008 did
show signs of defamation. The first
indications of impending disaster.
This growing volcanic activity and more
frequent earthquakes of higher intensity
were what began to raise speculation
that the East African rift system is
finally on the move in the first place.
And they continue to increase rapidly.
In 1977,
Mount Nurongo on the western fault of
the two main rifts erupted, emptying a
lake of unusually liquid lava that
flowed at speeds of 60 km an hour, the
fastest lava flow ever recorded. It
erupted again in 2002, partially
destroying the city of GMA, and then
again in 2021.
Following a long period of relative
quiet, the Alono Lengai in Tanzania has
also been more active since 1983.
And then in September 2007, it suddenly
erupted in spectacular fashion. It
vented out huge amounts of lava which
continued well into 2008 before it
settled down once again.
Satellite monitoring has shown
defamations around the volcano,
suggesting more increased activity in
the magma below.
When volcanoes start to move and bulge,
it tells us that the pressure of the
underlying magma is increasing. And it's
exactly this type of movement that
precedes eruptions.
Something else to bear in mind here is
the type of lava. The Aldo Lengai
volcano in Tanzania is the only active
volcano known to produce natural
carbonetite lava. A unique type of lava
known for its unusual composition and
low eruption temperatures.
Most lava that emerges at the Earth's
surface is very hot, over a,000° C, and
soon solidifies at cooler temperatures.
The lava produced by Odono Leni,
however, is much different. It is high
in alkaline minerals in the form of
carbonates and low in silicates. Without
the usual chains of silica to give the
magma structure, it remains liquid at
much cooler temperatures, nearly 5 or
600° C. In volcano terms, it produces
cold lava.
This particular type of magma has about
the same consistency as olive oil,
allowing it to flow faster and further
than other types of lava. And that may
well be a crucial factor.
Typically, as lava rises through cracks
in the lithosphere, it cools. And
sometimes this cooling is enough for it
to solidify before it erupts out of the
surface.
The pressure of the magma can be
partially relieved by flowing into
weaknesses in the surface layers of
rock, creating what are called
intrusions without violent volcanic
eruptions.
When it does reach the surface, it
quickly cools and stabilizes. Whereas
lava that is more liquid and remains
liquid at lower temperatures flows much
further and much faster.
This causes more destruction more
quickly and across a much greater area.
When this type of eruption occurs at a
single volcano, such as from the Alono
Langai volcano, it is highly
destructive.
Concerningly, a similarly alkaline very
liquid lava is also erupting from Mount
Nirongo, 750 km away in the Democratic
Republic of Congo in the entirely
separate western fault of the rift
system.
We still do not fully understand the
properties of this magma plume. the
rising column of hot molten rock that is
pushing upwards and causing the African
continent to move and crack. If it is
unusually liquid, as the eruptions in
Tanzania and the Democratic Republic of
Congo suggest it could be, it will
behave very differently to lava flow
seen elsewhere in the world. It will be
much more likely to break through to the
surface and it will quite simply just
keep on flowing.
If the underlying pressure continues to
build and the rift fault still refuses
to spread apart, vast lava flows of this
type could scorch and cover large areas
of East Africa, turning them into
wastelands of barren black rock.
The effects would be felt across the
entire planet if the East African rift
system develops into what geologists
call a large ignous province or LIP.
Enormous outpourings of lava onto the
Earth's surface.
They occur when mantle plumes drive the
formation of divergent fault systems,
the very conditions we suspect are
creating the East African Rift. Unlike
seafloor spreading, which is a slow and
steady continuous process, LIIP events
are episodic occurring in bursts over
much shorter periods of time.
Because they release enormous amounts of
gases into the atmosphere, they are
associated with major climate shifts in
the Earth's geological record.
LIIP events are so extreme, they've been
shown to correlate precisely with all
the mass extinctions over the last 260
million years.
That of course is a worst case scenario,
but lava flows even on a much smaller
scale would still have dire
consequences.
The East African Rift system covers an
area more than 5 million km squared and
is home to over 120 million people.
Locally, this would spell disaster,
forcing people to flee their homes and
destroying agriculture.
If this should occur at the same time
that the entire planet suffers a
downturn in food production as a
volcanic winter sets in, there would be
starvation on an unprecedented scale,
not just in Africa, but globally.
Of
course, our saving grace here is just
how slow these changes are likely to be.
The ERS is opening at a rate of just 6
or 7 millime per year. So, we're talking
millions, if not tens of millions of
years before anything like this would
likely come into effect. These things
are happening, but they're happening on
geological time scales. Thankfully, not
human ones. As the earthquakes and
volcanic eruptions continue, scientists
will also continue to monitor the
movements of the land surrounding the
beautiful rift valleys and mountains of
Africa, hoping to detect signs of what
is happening under the surface.
Because the pressure is building and
something has to give. You get the
feeling that whatever the next chapter
of Earth's history will be, the
reshaping of this majestic continent is
slowly but surely underway. and will
redefine the very face of planet Earth.
Whatever happens in the future, the
shape of the African continent will look
very different one day. If you think
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