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