Here Is What A 'Supervolcano' Actually Is, And What It's Definitely Not
The word “supervolcano” is, well, not ideal – but it’s not really its fault. It’s like nectar to hungry media bees, keen to capitalize on any tiny, insignificant event occurring at or near a supervolcano by squeezing it into a scary-sounding headline or – worse – writing an entire fear-mongering tale about it, much to the chagrin of volcanologists everywhere.
It’s actually a technical term, but it doesn’t mean what you think it means. Again, this isn’t your fault; I’m a volcanologist, and its prolific misuse in the media has even tripped me up once or twice in the past. So, in case you were wondering, here’s a breakdown of what a supervolcano is, and what is most certainly is not.
The term “supervolcano” – and “supereruption”, by default – didn’t get much attention in the media prior to the turn of the millennium. In 2005, it was popularized by a docu-drama produced by the BBC and the Discover Channel that focused on the consequences of a supereruption event taking place at Yellowstone.
According to the United States Geological Survey (USGS), a supervolcano is any volcanic center that has explosively erupted at least 1,000 cubic kilometers (240 cubic miles) of fresh volcanic material in a sudden, violent manner – in a so-called supereruption – often producing a huge depression crater named a caldera. This rules out flood basalts, large effusions of lava that can spend a million years or so scorching the earth and massively altering the climate.
That is literally all there is to it. There are plenty of supervolcanoes all over the world, from Taupo in New Zealand to Toba in Indonesia. Some are potentially just dormant, whereas others are almost certainly extinct.
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Yellowstone, that now-infamous volcano hanging out in Wyoming, is in particular sensationalized in this way, with certain publications keen to herald the end of the world as frequently as possible to get those sweet, sweet clicks piling in.
The one that gets all the attention, as you might have guessed, is Yellowstone. It’s not clear why it is reported on far more than any others, but I suspect it’s down to the erroneous idea that a supereruption is imminent at any time, encouraged by a cannibalistic positive feedback cycle in which the media has essentially generated its own legend.
Incidentally, I’m acutely aware that I’m part of the media too. Rumors regarding a supervolcanic apocalypse pop up almost on a weekly basis these days, which is why I spend much of my time turning them into linguistic dust. The most bizarre of all didn’t actually involve Yellowstone, but a story about a supervolcano appearing in New England. The idea that Ben & Jerry’s ice cream – based in Vermont – could be annihilated by this fake pit of hellfire was particularly vexing, so I naturally felt compelled to say something on the subject.
If you’re to believe the headlines, though, Yellowstone is primed to blow constantly, which makes you wonder what the heck this primadonna pyrotechnics display is waiting for. It doesn’t matter what it is: from dead bison to a crack appearing in a neighboring National Park, to some, it’s a sign of a supereruption. Whenever this happens, USGS staff members are inundated with phone calls from the panicked public – an increasingly unwelcome distraction when there’s actual volcanic eruptions and monitoring to deal with.
As experts are acutely aware, Yellowstone’s two-step magma reservoirs now more than 15 percent molten, whereas any eruptive activity requires around 50 percent molten material to be present. Even if it did erupt, it’d be more likely to be a lava flow or a hydrothermal blast, two surficial volcanic expressions that have occurred far more frequently throughout the beast’s geological history.
Yellowstone has experienced two supervolcanic eruptions in the last 2.1 million years, with another powerful event not quite making the cut, volume-wise. Considering the North American plate is moving around over a stationary, superheated mantle plume – the heat source that generates so much magma in the crust there – Yellowstone will eventually “die” as its underlying power is slowly removed. There may never be a supereruptive event there again.
The best analogy I have here is to Olympic medals. Sure, the volcano may have got the gold medal twice with those two supereruptions, but it doesn’t mean it’ll ever get that same spot on the podium again during the next Olympic Games. Perhaps it’s already retired in that sense.
Yes, it’s an active volcanic center. You have earthquakes and surface deformation, but that’s to be expected – it’s just doing what a volcano does. No-one’s shocked by all the surface geothermal activity, like those glorious (but frightfully deadly) hot springs and geysers. They may be fueled by the subterranean fire and fury, but because they happen all the time in plain view, it’s just perceived by the public as par for the course.
Small earthquakes and land movement happen near-constantly too, as the USGS is acutely aware, but as no-one in the public notices this, but instead sees terror-inducing headlines about them, this makes Yellowstone still seem like a threat.
There’s a chance that Yellowstone may engage in a supereruption one day. Yes, it would be an unmitigated social and economic disaster, if not world-ending. Right now, though, it’s really not worth worrying about. You couldn’t even use a nuke to set it off.
The USGS, to the best of their ability, peg the odds of a supereruption occurring this year as one-in-730,000 – very low odds indeed. Technically, you should be far more worried about dying in a car crash or simply falling over a bit awkwardly. Someone recently suggested that the odds of a Yellowstone paroxysm is still a lot higher than the chances of them winning the lottery’s top-tier jackpot prize, but that’s not how probability works. There’s only one volcano here, not hundreds of millions vying for the same prize.
Supervolcanic centers are potentially very dangerous, yes, which is why they are heavily monitored and researched. There’s a lot that volcanologists still don’t understand about them. They’re fascinating colossi, and they absolutely deserve our attention – but not in the way they’re often pushed to be perceived by certain media outlets.
Instead, we should focus on other volcanoes around the world, particularly those that are seen as unusually quiet and that are surrounded by plenty of people. In the 20thcentury alone, tens of thousands of people died from volcanic eruptions, and the hazards styles are plentiful: from mudflow-like lahars and pyroclastic flows – the two big killers – to volcanically induced tsunamis, gas emissions, debris fallout and even indirectly exacerbated epidemics, these are the real killers, not supervolcanoes.
Fortunately, scientists are on the case. From monitoring the silent Cascades in North America to leading relief efforts on the ground near Guatemala’s Fuego, from keeping people away from the dangers of the ongoing Kilauea eruption to comprehending the heartbeat of Campi Flegrei, volcanologists are working around the clock to better understand these beasts, so that we can do our best to co-exist with them, and perhaps even tame them a little.
Supervolcanoes are scientific wonders too, but the term “supervolcano” itself is now a little bit silly. It still remains a technical term, but at this point it’s being given the Geostorm treatment by the tabloids. It’s less than the sum of its parts, and not something to lose sleep over.
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