5 Things You Didn’t Know About Supervolcanoes
by Katie Slivensky
Maybe you’ve heard of the supervolcano lurking under Yellowstone National Park: a volcano that — if it erupts to its full potential — could wipe out most of North America and throw the world into a decade of winter. If you haven’t, you’re thinking about it now, aren’t you?
I first learned about this beast during a geology field course with the University of Michigan back in 2005. The supervolcano has captured my curiosity ever since — enough so that I used it as the basis for my newest novel, THE SEISMIC SEVEN.
As someone who immediately fell in love with Yellowstone National Park the first time I set foot in it, I was fascinated to learn that there’s a reason it has so many amazingly unique geological features, such as hot springs and geysers: it’s sitting on top of an alarmingly gigantic magma chamber — a massive hot spot that’s been spawning volcanoes for millions of years. Because of this, Yellowstone has experienced super-eruptions on at least three separate occasions: 2.1 million years ago, 1.3 million years ago, and 630,000 million years ago. But did you know it’s not the only supervolcano out there? And what exactly is a supervolcano, anyway?
1. The term “supervolcano” is actually pretty new.
It was rarely used in scientific literature until the 21st century and mostly caught on due to pop culture references. Even now, it doesn’t have an official definition, but the United States Geological Survey (USGS) does state that the term, “implies a volcanic center that has had an eruption of magnitude 8 on the Volcano Explosivity Index”.
What that means is that a volcano that’s had at least one eruption containing over 1000 cubic kilometers (240 cubic miles) of rock and ash any time in the past can be referred to as a supervolcano. If 1000 cubic km doesn’t sound like much for some odd reason to you, Mt. Saint Helens — the biggest eruption in U.S. history — had an eruption of only 0.7 cubic km of material. While most of that debris fell within its immediate vicinity, there was still plenty extra to leave dustings of ash over ten states. Meanwhile, in the Yellowstone super-eruptions, exploding lava, ash, and rock piled up meters-thick well over ten states away, and dustings of ash circled the entire globe.
Yeah. There’s a reason people started calling it a supervolcano.
2. Supervolcanoes form calderas — not cones!
So why don’t we have the world’s tallest volcano in the middle of the country? Well, that classic cone-shape rising from the ground is never the result of a super-eruption. When something as powerful as Yellowstone erupts, the earth below collapses on itself as a crater-like depression, known as a caldera. When you visit Yellowstone, you’re literally standing on the supervolcano at pretty much every moment, as the Yellowstone caldera is about 52x72 km (34x45 miles) across.
3. Yellowstone isn’t the only supervolcano.
There are over a dozen known supervolcanoes around the world. Indonesia, New Zealand, Italy, Bolivia — these massive volcanoes really are everywhere. Yellowstone has just become more popularized by the media, despite not having erupted for over half a million years. The most recent super-eruption was the Oruanui eruption in New Zealand approximately 26,000 years ago. And the one before that — the Lake Toba eruption, 74,000 years ago in Indonesia — is in contention as one of the largest volcanic eruptions in the entire history of the world.
4. Volcanic Winter is a real thing.
Speaking of the Lake Toba eruption, that’s a perfect example of an eruption causing global temperatures to drop. After all, it’s not just the lava and explosion that makes a supervolcano so dangerous: it’s the after-effects. In the case of Lake Toba, there is debate as to how great the effects of this volcanic winter were, but some average estimates say that temperatures fell by up to 5 degrees Celsius (9 degrees Fahrenheit). Why does this happen, though?
It’s not quite as simple as dust and ash blotting out the sun. Most of the damage is actually done by sulfuric gasses entering the atmosphere, ultimately creating aerosols that reflect sunlight back into space rather than allowing it to reach Earth and warm the planet up.
Result: worldwide winter.
5. In positive news: Yellowstone isn’t about to erupt. No supervolcano is.
Scientists agree — the risk of Yellowstone erupting naturally any time soon is, thankfully, absurdly small. So, we can all breathe easier with that in mind!
However, if you are a fan of the what-if (and what good scientist isn’t?), I recommend checking out my newest action-adventure novel, THE SEISMIC SEVEN. Seven young teens find themselves up against the eruption of Yellowstone’s supervolcano and need to band together to do what every adult insists is impossible: stop it.
About the author:
Katie Slivensky has worked and volunteered at zoos and museums since age eleven, which has resulted in a life of unique adventures. She’s fallen down a cliff in pursuit of fossils, helped separate fighting rhinos, and piloted an astronaut through space. (Okay, that last one happened in a planetarium. But the astronaut was real!) Katie grew up in Michigan and currently lives just outside of Boston with her two completely absurd cats, Galileo and Darwin. She is also the author of THE COUNTDOWN CONSPIRACY. Find her online at www.katieslivensky.com.
