In 2021, Mount Nyiragongo erupted.
The fastest lava in the world started
gushing towards the city of Goma and Lake Kivu.
Scientists were worried that this deadly event
could trigger something even worse deep within the lake.
An event that cannot be seen or heard
but could kill millions.
It's called a Limnic Eruption.
Yes, Limnic Eruption fortunately are rare
because they're also incredibly, incredibly dangerous.
Around the world, in very specific locations
you have these lakes that are normally very deep
and unlike other lakes, they don't kind of overturn
and squish around by the seasons very much.
So these lakes first have to form in areas
that are tectonically or volcanically active.
When you have magma shifting about
deep below the surface.
This magma often has gases trapped in it.
Carbon dioxide is a really common one.
If you have a lake that's incredibly deep
the lake acts as basically a storage device
for this gas because the lake is so deep
and the water at the bottom of the lake
is under so much pressure that it
acts as kind of like a vault for this gas
and the worry is that if you fill up
the vault with too much of this gas
it will explode out of the lake.
So it's a rare phenomenon but it's unfortunately one that
when it does exist, it's incredibly hazardous.
There are two ways in which these lakes
can explode and release this toxic gas.
The first is over saturation,
Where there's so much gas stored that
It cannot take any more and needs to be released.
The second is where something happens that
causes a sudden mixing of the water.
The troubling thing for a geologist
is that one of these killer lakes
lies at the foot of Mount Nyiragongo.
Lake Kivu.
The concern is that large volcanic activity
could lead to underground lava flows
which, if they reach the lake, could cause the colder
dense water to warm and rise to the surface
which could potentially trigger an eruption.
And that's what got everyone on edge in 2021.
Something local biologist Prince Kaleme
who studies the lake, remembers all too well.
To be clear, these eruptions aren't just theoretical.
They're very real and they've happened before.
Most recently in August, 1986.
The first accounts have started coming from
northwest Cameroon about the disaster
caused by a poisonous cloud from a volcanic lake.
Residents in the area say around 90% of people
in the surrounding villages were killed by the toxic fumes.
No one can kind of agree what caused the eruption.
There's arguments it could have been
an earthquake, maybe it was a landslide.
But something basically caused all this trapped
carbon dioxide to just erupt out
and this carbon dioxide just cascaded downslope
and killed 1700 people in their sleep
and, you know, many more animals.
And I think, you know, because it just
wiped out all these villages so quickly
and so stealthily, like no one knew what
had happened until people turned up
the next day and just saw all these people dead
with no apparent external injuries.
So it's quite a terrifying sight to behold.
But unfortunately, this kind of disaster
could happen again at that lake or other lakes
around the world if something's not done about them.
There was no warning.
The CO2 flooding down from the lake
had no smell and no visible signs.
That eruption in 1986 really kind of underscored
how dangerous these lakes could be.
It really made a point of this kind of disaster can happen
and I think it really woke up the scientific community
but also just the region to the
dangers that these lakes can pose.
After the eruption at Lake Nyos scientists
began looking for solutions.
Michel Halbwachs was convinced there
was a way to avoid another disaster
by releasing the trapped gas at the bottom.
But first he had to prove it.
And that's exactly what they did.
After the successful demonstration
the team installed larger permanent systems
which successfully degassed both lakes in Cameroon
preventing another disaster and potential loss of life.
The efforts were extremely successful
and the lakes have now been declared safe.
Now attention has turned to solving the issue of Kivu.
There are some upsides and downsides.
The downsize being its size, 2000 times bigger than Nyos.
Degassing it is a huge undertaking.
The upside is that one of the gases in Kivu
that's causing the pressure is methane
a gas that can be used to create energy.
In the case of of Kivu, the situation
is a very different one because the methane gas
which causes most of the gas pressure
has an economic value and so the logical thing
is then to use the gas and then they have
the double win win situation producing energy
at the same time and as as reducing the risk.
Once the methane is basically used up
and only the CO two is left
then the danger is very low.
Then basically the danger has been removed.
A power plant has been built floating on Kivu
and is currently producing 25 megawatts of power.
In the next few years they hope to increase this to 100
doubling the total amount of energy production.
for the entire country.
A welcome benefit for many living in the region.
It's been suggested that a safe and reasonable timescale
to use up this methane is around 50 to 100 years.
So it's feasible in the near future
this killer lake could be declared safe
and it couldn't come any sooner.
Still to this day the effects of these eruptions
serve as a reminder that if nothing is done
the unthinkable could occur.