What If Yellowstone Erupts Again?

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What If Yellowstone Erupts? </h4

Natural disasters are some of the greatest and the most unpredictable threats to humankind. Even with early warning systems in place, it’s possible for major cities to be destroyed at any time… by hurricanes, tornadoes, earthquakes and volcanic explosions. But one disaster has loomed particularly large in the media for decades, with repeated claims that we’re overdue for a major event.

This is Unveiled, and today we’re answering the extraordinary question; what if Yellowstone erupts?

In recent years it’s been a go-to topic when thinking about the apocalypse, but the supervolcano in Yellowstone National Park is actually much less active than some corners of the media make it seem… with regular, sensationalist articles claiming that we’re due a monster eruption in Wyoming “any day now”. The idea that an event is imminent does generally come from our knowledge of past supervolcanic eruptions in the region, of which there have been three: one 2.1 million years ago, another 1.3 million years ago, and the most recent 640,000 years ago. And so, judging by the gaps between those three dates, some say that we’re fast approaching (or even are inside) the prime time for another eruption. Nevertheless, basing all our fears on an average gap between three numbers… perhaps isn’t all that reliable. And the chances are still that if Yellowstone does erupt again, then nobody on Earth today would be alive to see it. And then, even if it did blow tomorrow, it’s also possible that we’d get a volcanic eruption that isn’t a super-eruption. That Yellowstone would blow, but it wouldn’t blow to the max. Volcanoes don’t care all that much about how humans try to classify them. The effects that they could cause exist along a scale. So, say Yellowstone erupted but not to its full potential… the event would still be destructive, but not any more (or less) apocalyptic than others like it. 

Still, there is no avoiding the full, heightened and devastating potential that Yellowstone does have. Supervolcanoes are classified by the power of their past eruptions. So, for any volcano to count as “super”, it has to have had a “super-eruption” in its past, which is an eruption at 8 or higher on the scale we use to measure these disasters; the Volcanic Explosivity Index. More specifically, a verified supervolcano has to have an eruption deposit larger than 240 cubic miles. And, because there’s no category higher than “super”, this means that the deposit is effectively limitless - ranging from 240 up to 1,000 cubic miles or more. 

The reason these eruptions are so large is that they occur when vast, underground chambers fill with so much magma they burst. In super-eruptions, the volume of magma is so great that an enormous depression forms in the ground when the chamber collapses; called a caldera. Yellowstone National Park is situated inside of three volcanic calderas - created by its three previous eruptions - so it really is a hot spot for this type of thing! Interestingly, though, Yellowstone’s previous explosions aren’t thought to have been the largest the world has ever seen, and any of our planet’s other supervolcanoes have the potential for huge destruction, too. Yellowstone is simply the most notorious; it’s the one that most people have heard of, and many people fear. 

So, since we can’t stop it from one day erupting, what exactly will happen if – or when – it does? 

For starters, the activity we most associate with volcanoes – deadly, flowing lava – wouldn’t be the most pressing problem, unless you were right at the center. Lava flows would be relatively small, slow and easily contained within the park, so you wouldn’t have to overly worry about getting covered in molten rock. In fact, if you were that close to begin with - close enough to be dodging the early lava - then you may have already been killed by the initial blast of the eruption itself. Some have claimed that it would be as powerful as an 875,000 megaton explosion going off (at least!) in the heart of the Midwest. 

Ash, on the other hand, is a totally different story. The biggest danger Yellowstone poses is an enormous pyroclastic flow, which is a giant and fast-moving cloud of toxic gas and volcanic matter. It’s this that will start to spread ash across the US, with the effects potentially worsened and quickened depending on wind speed at the time. It’s commonly said that a supervolcanic eruption could produce enough ash to block out the sun, plunging us into a volcanic winter and another ice age. It’s a contestable issue, but there is some evidence to back it up. For example, it’s theorized that the eruption of Lake Toba, 74,000 years ago, may have itself triggered a millennia of global cooling; so something similar definitely isn’t out of the question for Yellowstone. 

Next, and if the initially-less-concerning lava causes forest fires in the park, then this would further increase the output of ash. So much so that it’s thought that 500 square miles around the volcano itself would be quickly destroyed - choked and smothered by the cloud. On a wider scale, it’s predicted that every single mainland US state as well as parts of southern Canada and northern Mexico would experience at least some of the debris. And even thousands of miles out, this ash is so much more than just an eyesore! It could render huge regions of North America unsuitable for farming and agriculture, sparking famines and polluting much of an entire continent’s worth of water supply. And, since the United States is Earth’s largest economy, it’s a disaster which would have ramifications for the entire world… even in places that mightn’t see any of the volcanic ash or gas.

In terms of loss of life, a Yellowstone eruption would inevitably cause some extinctions; with endemic species in the surrounding area almost certainly wiped out. And, depending on exactly how far and how quickly the ash cloud travels, toxic debris could reach the ocean, causing yet more ecological devastation. Humankind as a whole would survive, but North America would suffer an untold list of casualties, as well as massive upheaval and displacement. If Yellowstone erupts with full force then people will lose their homes, suffer massive injury, and many will die.

To a certain extent, though, there may be opportunity to plan for the disaster. One positive note is that volcanoes don’t usually just erupt out of nowhere, especially not the most destructive ones. There are plenty of signs that geologists look for when they’re trying to predict whether one is liable to blow; including seismic disturbances, an increase in sulfur dioxide released from the ground, and even a change in the behavior of animals. Molten rock flows below the surface are difficult to measure, but they’re also the best indicator of a magma chamber slowly filling up. The problem here, though, is that notable change can happen weeks or months before an eruption, but sometimes it’s years or even decades. Where volcanoes are concerned there is always a degree of uncertainty, but there’s usually at least a little time to prepare.

As such, when the Yellowstone question truly becomes a matter of “when?” and not “if?”, we should see widespread countermeasures put in place - to try to at least limit the damage. Evacuation plans and drills within 500 miles of the park; huge stockpiles of food and water across the continent; emergency housing built along the coast, as far away from the imminent eruption and ash cloud as possible - they’d all need to be considered. Yellowstone would likely become a complex diplomatic issue, too, as refugees from the worst-affected regions look to the international community for help. Meanwhile, some living further afield might rely on underground bunkers to keep them safe… in which case the authorities would need to register (and probably approve) all of them, so that they’d be able to relocate everyone once the worst of the disaster had passed. Given enough time, we could perhaps try to save those endemic and local plants and wildlife at risk, putting animals in conservation-oriented zoos, and plants in purpose-built structures like the Svalbard Global Seed Vault.

Quite what the world would look like once the dust had settled, though, is difficult to imagine. Underground bunkers, temporary housing and evacuation drills could save us from the immediate effects, but the recovery period would be long and grueling - with huge areas covered in layers of ash potentially meters thick (depending upon how close to the volcano you get). The prospects of anything growing in the near-future would be low. And, even in the far-future, a super-eruption would change and disrupt soil types and farming practices for generations. The legacy of Yellowstone could shape our planet for centuries (even millennia) after the worst happens.

That said, volcanoes are a natural feature of the environment, and are actually integral to how many ecosystems work. The natural world relies on them in many ways. So, should Yellowstone erupt, it ultimately wouldn’t trigger total Armageddon. The planet itself would definitely recover from such an event, just as it has recovered from all the super-eruptions of the past.

For now, there’s no denying that a worst-case-scenario; a full potential Yellowstone eruption would have a massive effect on life on Earth. But, at the same time, it wouldn’t be the first time that humanity had faced a disaster on this scale. Again, the Toba catastrophe was 74,000 years ago, and our species lived to tell the tale. In fact, it may have even been bigger than Yellowstone, but humanity survived it even without a lot of the prior knowledge that we now have.

It would be devastating and dangerous; it’d create all new landscapes across an entire continent; it could trigger wide-reaching problems with the global economy; and Yellowstone National Park itself would never look the same. But, after all the tragedy, ruin and desperation, life would still find a way to continue. And that’s what would happen if Yellowstone were to erupt.