Weird Places: The Lava Lake in Antarctica

Weird Places: The Lava Lake in Antarctica


Earth is covered in lakes. Mostly these are cool, watery affairs full of life and great for a relaxing vacation. Lava lakes are a little less serene: they’re scorching, seething pools of molten
rock. They’re also pretty rare, outside of MineCraft permanent lava lakes only exist in a few places
around the globe. One of the strangest lava lakes is atop Mount
Erebus, on the frozen continent of Antarctica. Probably the weirdest thing about this lake
is that it’s constantly releasing gas, and the composition of that gas changes on
a roughly ten-minute cycle. Erebus was a Greek god, the son of Chaos which is kinda fitting for a place made of
ice and fire. Mount Erebus is the tallest peak on Ross Island, which lies close to the Antarctic mainland and is usually connected by ice sheets. It’s an active volcano that’s been bubbling
away for decades, occasionally throwing off larger eruptions. The lava lake is around 20 meters deep, and it sits in a crater which is itself inside
Mount Erebus’s main crater. Under the lake is a conduit, a tube that leads
down to a chamber full of magma underground lava, in other words. The lake is basically like a bowl with a hole
in the bottom sitting on top of a pipe – like a sink, I
guess you could say except it goes the other way: it doesn’t
go down, it goes up. And all of it’s about a thousand degrees
Celsius. Even in the frigid Antarctic air, the lake’s
surface won’t cool into solid rock thanks to convection currents that feed the
lake with a steady supply of hot stuff. Hot magma rises to the top of the lake, then
spreads outward, cooling off along the way. As it cools it gets denser, so it sinks back down again – and the convection
cycle continues. Lava lakes need that crater, conduit, and
magma chamber combo to exist, and not many volcanoes have all those components
so well aligned. That’s why molten lava lakes are super-rare there are only about five on Earth that have
remained persistently active in recent years. So the Mount Erebus lava lake is an unusual
and remote place, but thanks to some intrepid scientists, it’s
an area of active research. Scientists have braved freezing slopes and
burning lava bombs that’s the technical term for flying blobs
of lava and they’ve installed remote sensors to
keep tabs on the lake 24/7. One mystery they’re working on is the lake’s
persistent gas emissions. For years, Erebus has been steadily releasing
a gas plume, and there’s a weird cycle to it. Over the course of ten minutes or so, there’s a repetitive shift in both the amount
of gas produced, and its composition — the overall mix. For example, the carbon dioxide to carbon
monoxide ratio changes, as do emission levels of water vapor and sulfur
dioxide. Researchers have been trying to figure out
why there’s this repeating cycle, and based on sensor data and computer modeling, they think it has to do with two main sources
of gas. One comes from the conduit, and the other
comes from diffusion in the lake. The carbon dioxide-rich gas is always rising
up from the conduit, and it’s basically constant the amount and composition doesn’t really
change. But the conduit also occasionally, like every
ten minutes or so, burps out a large blob of magma from deeper
in the chamber, like a kind of literal one-way lava lamp. Once a blob gets near the surface of the lake
it releases a fresh set of gases, which adds to the total amount of gas detected and changes the overall composition because
it’s rich in water vapor and sulfur dioxide. In addition to these shorter cycles, the lava lake also has what researchers call
explosive degassing. These less frequent but more impressive belches
cause small eruptions, hurling lava bombs into the main crater. The two systems seem to work independently. The composition of the gas from the explosive
degassing is different from the gas from the shorter cycle, and appears to come from much deeper in the
volcano’s magma chamber. There is still a lot left to learn about Erebus,
and lava lakes in general. For example, there are gas cycles with other
cycle lengths that aren’t as well studied. Working out if they’re connected, and how, will build up a better model of the inner
workings of Mount Erebus. Mount Erebus also contains a rare type of
magma called phonolite. It’s much thicker than the more common basalt
variety, which probably affects the fluid dynamics
inside the magma chamber and lake. So hopefully the recent studies on Erebus
will be useful for scientists working on other lava lakes
around the world. These lakes may be rare, but having good models from the few examples around the world will
help geologists understand the similarities and differences
between them and the overall rules about how they work. Thanks for watching this episode of SciShow, brought to you by our patrons on Patreon. If you want to help support this show, you can go to patreon.com/scishow and become
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