January 9, 2019 • 5 mins
Given the right depth, temperature, and access to volcanic gases, lakes can explode and kill thousands in the process. Learn how these limnic eruptions happen in this episode of BrainStuff.
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Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
Lauren Vogelbam. Here today we're talking about a rare but
incredibly deadly natural phenomenon, exploding lakes a k A. Limnic eruptions.
A limnic eruption is what happens when deadly gases like
carbon dioxide explode out of volcanic lakes. Sometimes the carnage
(00:24):
unfolds on multiple fronts. Just as lethal clouds suffocate humans
and animals, the abrupt displacement of water is liable to
create tsunamis. That exact combination of events killed more than
seventeen hundred people one grim summer day in nine six
in the West African country of Cameroon. And now scientists
wonder if an even bigger limnic eruption is in the making.
(00:46):
But how does such an explosion happen? Let's start with
water pressure. Water pressure increases with depth. That's why scuba
divers can't venture too far below the surface without the
right equipment. The force that's exerted upon a submerged object
by the weight of all the liquid above it is
called hydrostatic pressure. Normally, this pressure intensifies by fourteen point
(01:06):
five pounds per square inch or one kilo pascals or
one bar for every ten meters of water depth. That's
about thirty three ft. But the key to limnic eruptions
lies in temperature. The gases dissolve more easily in cold,
high pressure water. Limnic eruptions can only occur in deep
bodies of water with a lot of hydrostatic pressure at
(01:28):
the bottom. There must also be a significant difference in
both the pressure and temperature between the surface water and
the lower depths, With the lower depths being much chillier.
Stratification will act like a barrier, keeping that dissolved gas
confined to the lake bottom, where it can't depressurize and
escape out into the atmosphere. Because it's trapped, the dissolved
(01:49):
gas accumulates in massive and potentially deadly quantities. Explosions are
impossible in lakes whose lower and upper water levels intermingle
on the regular For build up to occur, the water
also needs a continuous supply of some highly soluble gas,
like carbon dioxide or methane, and that's where volcanism comes in.
At localities with active volcanoes, buried magma is liable to
(02:12):
send methane, CO two and other gases seeping up through
thin sections of Earth's crust. If a lake is overhead,
the gas may pass right into the water, traveling by
volcanic fence and other roots that brings us back to
Cameroon and to its lakes. NEOs and Monoun both are
located in a volcanic field, and both lake bottoms are
oversaturated with carbon dioxide, which underlying magma sends their way.
(02:36):
On August fifteenth, some of the deep water in Monoun
that had been loaded up with the dissolved gas ascended
to the surface. No one knows why this happened. It's
possible that heavy rainfall and an earthquake or landslide displaced
some of the lake bottom water. Regardless, as the water rose,
the dissolved carbon dioxide lurking inside it became depressurized and
(02:57):
formed bubbles. Those bubbles drove even more of the water
up to the top of the lake, resulting in a massive,
foul smelling cloud of carbon dioxide gas. Under the wrong
set of circumstances, this gas is extremely dangerous to people.
Large quantities of CEO to cling to the ground and
displace oxygen, which can lead to death by suffocation. The
eruption killed at least thirty seven people, and two years later,
(03:20):
on August twenty one, six, Lake Neo's experienced a limnic
eruption of its own. Once again, there was a sudden,
mysterious upheaval of carbon dioxide laden water from its frigid,
high pressure depths, but this time the body count was
much higher. Carbon dioxide from the Lake Neo's disaster killed
approximately one thousand, seven hundred forty six people and more
(03:40):
than three thousand, five hundred domestic animals. Somewhere from three
hundred thousand to one point six million metric tons of
c O two gas burst out of the water with
enough force to set off a twentys tsunami that's about
sixty six ft tall. That was the last recorded limnic eruption.
If you're worried about a killer limnic eruption coming to
a lake near you, University of Michigan geoscience professor yolks
(04:02):
Jung says you probably shouldn't be. Lake NEOs and Lake
Monoon are located just above the equator, where it tends
to be warm all year round, and there's just no
way for a limnic eruption to happen in a temperate
body of water. In places where seasonal temperatures vary widely,
like in the Great Lakes, lake surfaces often cool down,
causing the water at that level to sink and swap
(04:23):
places with the layers of water beneath it. Any gas
is dissolved in there don't stay trapped. They're released as
they depressurized nearer to the surface. No gas accumulation, no eruptions. However,
Young and many of his colleagues have taken a healthy
interest in Lake Kivu, an up and coming vacation destination
on the border of Rwanda and the Democratic Republic of
the Congo. Why because it seems to have all the
(04:46):
necessary criteria for a truly colossal limnic eruption. The lake
contains about ten point five billion cubic feet of carbon
dioxide that's about three billion cubic meters, and two billion
cubic feet of methane about up sixty billion cubic meters,
all lurking near the bottom. Were those gases to explode
from the lake's surface, the two million people who live
(05:08):
around Kivu might find themselves in jeopardy. One possible solution though,
harvest those very gases as a possible energy source by
an extraction barge. Kivu Wat is a one of a kind,
two million dollar facility that uses an offshore barge to
draw up water from the lake. It then siphons off
the methane and sends it to a power plant, generating
(05:28):
electricity for the area. When life gives you lemons, turn
it into electricity. Today's episode was written by Mark Mancini
and produced by Tyler Clang. For more on this and
lots of other powerful topics lurking in the depths, visit
our home planet has Stuff works dot com.
Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,
Lauren Vogelbam. Here today we're talking about a rare but
incredibly deadly natural phenomenon, exploding lakes a k A. Limnic eruptions.
A limnic eruption is what happens when deadly gases like
carbon dioxide explode out of volcanic lakes. Sometimes the carnage
(00:24):
unfolds on multiple fronts. Just as lethal clouds suffocate humans
and animals, the abrupt displacement of water is liable to
create tsunamis. That exact combination of events killed more than
seventeen hundred people one grim summer day in nine six
in the West African country of Cameroon. And now scientists
wonder if an even bigger limnic eruption is in the making.
(00:46):
But how does such an explosion happen? Let's start with
water pressure. Water pressure increases with depth. That's why scuba
divers can't venture too far below the surface without the
right equipment. The force that's exerted upon a submerged object
by the weight of all the liquid above it is
called hydrostatic pressure. Normally, this pressure intensifies by fourteen point
(01:06):
five pounds per square inch or one kilo pascals or
one bar for every ten meters of water depth. That's
about thirty three ft. But the key to limnic eruptions
lies in temperature. The gases dissolve more easily in cold,
high pressure water. Limnic eruptions can only occur in deep
bodies of water with a lot of hydrostatic pressure at
(01:28):
the bottom. There must also be a significant difference in
both the pressure and temperature between the surface water and
the lower depths, With the lower depths being much chillier.
Stratification will act like a barrier, keeping that dissolved gas
confined to the lake bottom, where it can't depressurize and
escape out into the atmosphere. Because it's trapped, the dissolved
(01:49):
gas accumulates in massive and potentially deadly quantities. Explosions are
impossible in lakes whose lower and upper water levels intermingle
on the regular For build up to occur, the water
also needs a continuous supply of some highly soluble gas,
like carbon dioxide or methane, and that's where volcanism comes in.
At localities with active volcanoes, buried magma is liable to
(02:12):
send methane, CO two and other gases seeping up through
thin sections of Earth's crust. If a lake is overhead,
the gas may pass right into the water, traveling by
volcanic fence and other roots that brings us back to
Cameroon and to its lakes. NEOs and Monoun both are
located in a volcanic field, and both lake bottoms are
oversaturated with carbon dioxide, which underlying magma sends their way.
(02:36):
On August fifteenth, some of the deep water in Monoun
that had been loaded up with the dissolved gas ascended
to the surface. No one knows why this happened. It's
possible that heavy rainfall and an earthquake or landslide displaced
some of the lake bottom water. Regardless, as the water rose,
the dissolved carbon dioxide lurking inside it became depressurized and
(02:57):
formed bubbles. Those bubbles drove even more of the water
up to the top of the lake, resulting in a massive,
foul smelling cloud of carbon dioxide gas. Under the wrong
set of circumstances, this gas is extremely dangerous to people.
Large quantities of CEO to cling to the ground and
displace oxygen, which can lead to death by suffocation. The
eruption killed at least thirty seven people, and two years later,
(03:20):
on August twenty one, six, Lake Neo's experienced a limnic
eruption of its own. Once again, there was a sudden,
mysterious upheaval of carbon dioxide laden water from its frigid,
high pressure depths, but this time the body count was
much higher. Carbon dioxide from the Lake Neo's disaster killed
approximately one thousand, seven hundred forty six people and more
(03:40):
than three thousand, five hundred domestic animals. Somewhere from three
hundred thousand to one point six million metric tons of
c O two gas burst out of the water with
enough force to set off a twentys tsunami that's about
sixty six ft tall. That was the last recorded limnic eruption.
If you're worried about a killer limnic eruption coming to
a lake near you, University of Michigan geoscience professor yolks
(04:02):
Jung says you probably shouldn't be. Lake NEOs and Lake
Monoon are located just above the equator, where it tends
to be warm all year round, and there's just no
way for a limnic eruption to happen in a temperate
body of water. In places where seasonal temperatures vary widely,
like in the Great Lakes, lake surfaces often cool down,
causing the water at that level to sink and swap
(04:23):
places with the layers of water beneath it. Any gas
is dissolved in there don't stay trapped. They're released as
they depressurized nearer to the surface. No gas accumulation, no eruptions. However,
Young and many of his colleagues have taken a healthy
interest in Lake Kivu, an up and coming vacation destination
on the border of Rwanda and the Democratic Republic of
the Congo. Why because it seems to have all the
(04:46):
necessary criteria for a truly colossal limnic eruption. The lake
contains about ten point five billion cubic feet of carbon
dioxide that's about three billion cubic meters, and two billion
cubic feet of methane about up sixty billion cubic meters,
all lurking near the bottom. Were those gases to explode
from the lake's surface, the two million people who live
(05:08):
around Kivu might find themselves in jeopardy. One possible solution though,
harvest those very gases as a possible energy source by
an extraction barge. Kivu Wat is a one of a kind,
two million dollar facility that uses an offshore barge to
draw up water from the lake. It then siphons off
the methane and sends it to a power plant, generating
(05:28):
electricity for the area. When life gives you lemons, turn
it into electricity. Today's episode was written by Mark Mancini
and produced by Tyler Clang. For more on this and
lots of other powerful topics lurking in the depths, visit
our home planet has Stuff works dot com.
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