BrainStuff Classics: What Makes Some Lakes Explode?

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 classic episode of BrainStuff, based on this article: https://science.howstuffworks.com/environmental/earth/geophysics/what-makes-killer-lake-explode.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of iHeartRadio. Hey brain Stuff,
Lauren Vogel Bomb here with another classic from our podcast's archives.
This one covers a natural phenomenon that you probably don't
have to worry about, but that's nonetheless fascinatingly terrifying. Exploding lakes.

(00:24):
Hey brain Stuff, Lauren vogel Bomb Here. Today we're talking
about a rare but incredibly deadly natural phenomenon, exploding lakes
aka limnic eruptions. A limnic eruption is what happens when
deadly gases like carbon dioxide explode out of volcanic lakes.
Sometimes the carnage unfolds on multiple fronts. Just as lethal

(00:45):
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 nineteen eighty six in the West African country of Cameroon.
And now sign up. Wonder if an even bigger limnic
eruption is in the making. But how does such an

(01:05):
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 five pounds per square inch

(01:26):
or one hundred kilopaskels or one bar for every ten
meters of water depth. That's about thirty three feet. But
the key to limnic eruptions lies in temperature. 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 the bottom. There must also be

(01:48):
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 gas accumulates in massive and potentially

(02:09):
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 send methane, CO two and

(02:31):
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 vents 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

(02:52):
underlying magma sends their way. On August fifteenth of nineteen
eighty four, 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 earthquaker a landslide displaced some
of the lake bottom water. Regardless, as the water rose,
the dissolved carbon dioxide lurking inside it became depressurized and

(03:15):
formed bubbles. Those bubbles drove even more of the water
up to the top of the lake, resulting in a massive,
vowel smelling cloud of carbon dioxide gas. Under the wrong
set of circumstances, this gas is extremely dangerous to people.
Large quantities of CO two cling to the ground and
displaced oxygen, which can lead to death by suffocation. The
eruption killed at least thirty seven people, and two years later,

(03:38):
on August twenty first, nineteen eighty six, Lake NEOs experienced
a limit 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

(03:58):
and more than three thousand, five hundred demsic animals. Somewhere
from three hundred thousand to one point six million metric
tons of CO two gas burst out of the water
with enough force to set off a twenty meters tsunami
that's about sixty six feet 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

(04:19):
geoscience professor Yuxyu Jang 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

(04:40):
sink and swap places with the layers of water beneath it.
Any gas is dissolved in there don't stay trapped. They're
released as they depressurize nearer to the surface. No gas accumulation,
no eruptions. However, Jiang and many of his colleagues have
taken a healthy interest in Lake Kivu, an up and
coming vacation destination on the border of Rwanda A the
Democratic Republic of the Congo. Why because it seems to

(05:04):
have all the 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 hundred billion cubic meters
and two billion cubic feet of methane about sixty billion
cubic meters, all lurking near the bottom. For those gases
to explode from the lake's surface, the two million people

(05:25):
who live 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 hundred 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 electricity for the area. When life

(05:48):
gives you lemons, turn it into electricity. Today's episode is
on the article what makes killer Lakes Explode on HowStuffWorks
dot com, written by Mark Mancini. Brainstuff is production of
iHeartRadio in partnership with HowStuffWorks dot Com and is produced

(06:09):
by Tyler Klang. For more podcasts from my heart Radio,
visit the iHeartRadio app, Apple Podcasts, or wherever you listen
to your favorite shows.