When you picture a volcano, what do you see? I personally imagine a mountain sticking up into the sky. At the top of that mountain, I see a crater with a fiery hot lake boiling and roiling in it, or lava pouring down a slope like bright red candle wax, or massive clouds of grey ash exploding into the air.

It’s all incredible, powerful imagery, but it’s also really just the tip of the volcano-berg.

If I were to descend down through my imaginary volcano, moving down through layers and layers of earth, I’d find what might be an even more incredible feature: my volcano’s pulsing, fiery furnace of a heart, also known as its “magma chamber.” This is the reason that hot ash comes bursting up through the surface. It’s the original source of my lava and my crater lake. It’s where much of the important action in a volcano unfolds — and could hold secrets to help us better predict when a devastating eruption will occur.

The problem is that we know much less about magma chambers like this than we’d like to. We’re not even good at depicting them.

“We draw them as red balloons,” says Mike Poland, a geophysicist and scientist-in-charge at the Yellowstone Volcano Observatory. “They are not. But it’s a very difficult thing to represent.”

Magma chambers are so hard to represent because they’re so complex. They can be thousands of degrees Fahrenheit and have blends of solid material and hot liquid rock. These chambers have different temperatures in different spots, and different minerals melting at different heats or moving around in different ways. And, making things even more complex, there’s a multitude of different gases that might make pressure build up before an eruption.

But if we could better represent magma chambers — and just generally better understand exactly how they work — Poland says we might be able to dramatically improve our understanding of how volcanoes operate, and therefore be better able to anticipate what to expect from an impending eruption. But right now, because these chambers are so hot and so deep underground, it’s hard to plumb their secrets.

“We don’t have, like, the glass-bottomed volcano where you can just sort of look into and go like, Oh, that’s what’s going on,” Poland jokes.

But what if we could have a glass-bottomed volcano that we could sort of look into and go like, Oh, that’s what’s going on? What if we could build, say, a little observatory deep down under the ground, right in the hot little heart of a volcano? It sounds absurd, and yet…

“ There’s a project in Iceland,” Poland tells me, “They want to build a magma observatory. They want to drill into a magma chamber and put some monitoring equipment in the hole. … That would give us some idea of what’s going on in there.”

The project is called the Krafla Magma Testbed, or KMT, and the researchers working on it think it could revolutionize volcanology — and how we forecast eruptions.

But first, what’s missing from our volcano forecasts?

One of the key motivations for building an observatory like this is that volcanology has a prediction problem. On the one hand, volcanoes are much more predictable than, say, earthquakes — they tend to give us some warning signs before they erupt. But on the other hand, it’s hard to perfectly interpret those warning signs, which means the predictions volcanologists can make with our existing technology can be both incredibly helpful and frustratingly imprecise.

For example, for the last year or so, a potential eruption has been brewing at Mount Spurr, a volcano near Anchorage, Alaska. Twice in the last 100 years, eruptions from Mount Spurr have rained ash down on the city, clogging up roadways, shutting down the local airport (one of the busiest cargo ports in the world), and settling like a fine dusting of gritty, gray, unmelting snow on cars and lawns and leaves of trees.

People are understandably worried about a repeat performance, and the Alaska Volcano Observatory is monitoring the situation closely.

Matt Haney, the scientist-in-charge at that observatory, told me while he can be sure that the volcano is displaying several key warning signs, he can’t be sure exactly what the upcoming volcanic activity might look like — if there will be one eruption or many, exactly how intense they will be, or........

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