Roughly every 100, 000 years, our planet undergoesone of the most-violent catastrophes imaginable.
Supervolcanoes are to regular volcanoes whatsupermassive black holes are to regular black holes or the Incredible Hulk is to Hulk Hogan.
Bigger, badder, and infinitely more-terrifying.
Capable of ejecting over 1, 000 cubic kilometersof material, even the smallest supervolcano dwarfs any eruption in human history.
Mt St Helens, Krakatoa, Vesuvius… all aremere sparks against such infernos.
But while no supervolcano has erupted sincethe dawn of civilization, that doesn’t mean they’re gone.
If you live in America, you may have evenvisited one.
Yellowstone national park is famous for itsbeauty.
But just under the surface lies somethingfar uglier: a plume of molten rock that – were it to cause an eruption – could potentiallykill millions.
Where did this supervolcano come from, howlikely is it to explode, and what would happen to the world if it did? Today, Geographics is uncovering Yellowstone’sexplosive past… and taking a glimpse into its apocalyptic future.
The Exploding Earth On April 10, 1815, Tambora volcano in Indonesiaexploded with a force unprecedented in recorded history.
Over 3 days, 175 cubic kilometers of debriswas ejected into the atmosphere atop a plume of ash 45km high.
So much material was hurled into the sky thatit darkened the sun.
The following year, 1816, would become knownas the Year Without a Summer – a year in which ice froze rivers in August, flooding destroyedcrops, and famine and disease ran riot.
Thanks to these climactic effects, it’sthought as many as 82, 000 people across the globe died.
It was by far the biggest eruption since thedawn of human civilization, dwarfing even the Hekla 3 eruption that may have triggeredthe Bronze Age Collapse.
But here comes the kicker.
This apocalyptic volcano that affected theentire planet was just a regular ol’ volcano.
By contrast, were a supervolcano to explodetoday, it would make Tambora look like a Girl Scout bake sale.
In the history of the Earth, there have beenaround 50 known supereruptions.
The most-recent occurred at New Zealand’sLake Taupo about 26, 000 years ago.
But while a video about Taupo’s explosivepast would be great, that’s not what we’re here to discuss today.
No, we’re here to talk about the most-famoussupervolcano of them all: Yellowstone.
To get an idea of the how the Yellowstonesupervolcano formed, you have to go back in time.
Way, way back into prehistory.
Until roughly 66 million years ago, the entireYellowstone area was covered by an inland sea.
But then the Cenozoic era began, and broughtwith it a burst of volcanic activity.
Now, this was volcanic activity unrelatedto the modern supervolcano.
But it did result in the Absaroka mountainRange popping into existence, giving Yellowstone its northern and eastern borders.
However, it was what happened some 49 millionyears later that changed the park’s fate.
If you’d been floating above the North Americancontinent and watching the millennia pass on fast forward, it would’ve looked likea whole bunch of volcanoes suddenly started springing up around the Nevada, Oregon, andIdaho border.
Those volcanoes would’ve started marchingeast, popping up one by one on an 800km journey toward northwest Wyoming.
But this would’ve just been the view fromabove.
Underground, a very different story would’vebeen taking place.
Rather than the volcanoes themselves marchingnortheast, the reality was that the North American plate was slowly grinding southwestover a sunken bubble of magma.
Imagine a carpet being dragged across a warpedold wooden floor with a bump in it.
As the carpet moves, the bump would stay inthe same place, making different parts of the carpet rise up at different times.
In a very simple way, that was what was happeningin prehistoric America over millions of years.
Finally, some 2.
1 million years ago, thatbump found itself under a thin, threadbare piece of carpet marked Yellowstone.
It’s at this point that things got interesting.
Not long after the magma bump found itselfbelow Yellowstone, it gave its first supereruption.
Since we don’t have any records of a supervolcanoblowing, we don’t know what it would’ve actually looked like.
But we can guess.
Over thousands of years, magma, water vapor, and gasses would’ve built up inside the bump, until the pressure made it start togrow.
Stood on the ground, you would’ve seen adome, getting bigger and bigger.
Finally, it would’ve gotten so big thatthe edges started to tear, providing a release for the pressure below.
By the time you noticed that, though, yourlast chance to run would’ve been long gone.
The first Yellowstone supereruption was almostbeyond comprehension.
Over 6, 000 times the size of Mt St Helens, it released 2, 500 cubic kilometers of debris.
Over 15, 000 square kilometers of North Americawere coated in ash.
Where the magma blew, the Earth collapsed, forming a depression the size of Rhode Island.
In the aftermath, the gasses expelled would’vedimmed the sun, plunging the entire planet into a winter that lasted for years.
It was the first example of the supervolcano’sraw power.
It wouldn’t be the last.
The Great Eruptions In its two million years of existence, theYellowstone supervolcano has never again erupted with the force of its first major blast.
But even its two smaller supereruptions werestill what we’d call “pretty damn big.
” Take the supereruption of 640, 000 BC.
The third of Yellowstone’s three major explosions, it went up with the force of 2, 500 Mt St Helens eruptions.
That meant a plume of ash 30km high, so bigit left debris as far away as the Gulf of Mexico.
It meant gigantic, superheated clouds of rockand ash nearly 1, 0000C hot sweeping across modern Wyoming, burying the land beneath alayer over 100m deep.
Anything within 1, 000km of the eruption almostcertainly died.
In the aftermath, another gigantic calderaformed, this one capable of swallowing the whole of Samoa.
Even the smallest of the three supereruptions, the one that blew in between these two monsters, would’ve been an awe-inspiring sight tobehold.
Well, at least until it would’ve until itkilled you.
However, it would be wrong to think that theYellowstone volcano is only capable of planet-cooling blasts.
Between 640, 000 and 70, 000 BC, some 80 eruptionstransformed the Yellowstone landscape.
Although some created features we’d stillrecognize today – like the Pitchstone Plateau – none of them were even close to being Tambora-sized, let alone supereruptions.
It’s here we get to one of the biggest misconceptionsabout supervolcanoes: that, because of their size, anytime they blow it must be a supereruption.
The reality is that most supervolcanoes onlyrarely erupt at their full capacity.
They’re far more likely to just sit there, bubbling away, creating groovy effects on the surface.
Yellowstone volcano is a prime example ofthis.
All those steam vents, hot springs, and mudcauldrons you’ve seen in your auntie’s vacation photos? They’re all due to that great big magmachamber we talked about earlier.
Because the ground in Yellowstone is cracked, water is constantly worming its way down to the magma, getting superheated, and shootingright back up to the surface.
The 300 geysers in Yellowstone park – overhalf the total in the world – only exist because they’re on the surface of a volcano so bigyou can’t even see it.
So next time you roll out there in your RVand watch Old Faithful do its thing, just remember that the supervolcano below isn’tonly good for inspiring scary YouTube documentaries.
In fact, without that plume of molten rockunder Wyoming – a plume that stretches at least 960km down, and likely as far as 3, 000km- there wouldn’t be a national park for you to visit at all.
That’s because it was these outside signsof volcanic activity that made people think the area was worth preserving in the firstplace.
The Invisible Volcano On August 29, 1870, the gloriously be-moustachedGustavus Doane scaled Mount Washburn.
A Civil War veteran turned explorer, the 30-yearold Doane was in Wyoming as part of – as his name might suggest – the Washburn-Langford-Doaneexpedition.
At this point in American history, much ofthe interior was still a fascinating mystery.
The West had been tamed, but many of thoseplaces lying between the coasts were still the 19th Century equivalent of an olde timeymap marked “Here be monsters”.
It was a mere 43 years earlier that the firstdescription of Yellowstone had appeared in a newspaper; only 34 years earlier that thefirst rough map had been made.
In the decades since, trappers, explorers, and one priest had visited the area, but the stories they brought back of the landscapewere too fantastical to be believed.
At the moment Gustavus Doane started scramblingup the side of his mountain, the average American’s opinion of Yellowstone was basically “what’sYellowstone?”.
It was the Washburn-Langford-Doane expedition’stask to make sure that changed.
At long last, Doane reached the top of MtWashburn.
All around him stretched the wilds of Wyoming, the great, rugged view that would soon become known as Yellowstone national park.
To the south, the Rocky Mountains rose andfell, adding texture to the view.
But there was an anomaly.
As Doane squinted, he noticed there was abreak in the mountain range, a place where a flat circle of forest seemed to have beencrudely carved out the landscape.
Not long after, the explorer recorded histheory on it.
“The great basin, ” he wrote, “has beenformerly one vast crater of a now extinct volcano.
” It was the first time in history anyone hadrealized the explosive secret Yellowstone was hiding.
Prior to Doane’s expedition, humans hadbeen coming to the Yellowstone region for thousands of years.
We know this, because tools dating back to9, 000BC have been unearthed at sites across the park.
Since they’re from so far back, though, we have no idea who they belonged to.
The name of the people that produced thesetools has been lost to time as effectively as if it had been written on paper then droppedinto a raging river.
It wasn’t until the fifteenth century thatwe got a Yellowstone-based culture that still survives.
Known as the Shoshone or sometimes the Sheepeaters, the tribe settled the park around 1400 AD.
Quite what they made of all the strange lakes, geysers, and hot rivers wasn’t recorded, but we can assume it probably blew their minds.
That’s because minds being blown is a prettyconsistent feature of Yellowstone’s past.
When the first white people arrived in Yellowstone400 years after the Shoshone, their accounts were often laughed off by those living onAmerica’s coasts as the wild ravings of deluded woodsmen.
The idea of hot rivers and jets of boilingwater was simply too far-fetched; like if someone told you today about a secret placein Idaho with candy floss trees.
It didn’t help that the government’s officialexpedition to the area failed to reach it, leaving most people in the dark about theawe-inspiring landscape.
But as the 19th century rolled on, more explorersand trappers started coming back from Yellowstone with similar tales, until it was decided thismythic place needed to be surveyed properly.
And so it was, in 1870, that both Doane’sthree-name expedition and the near-simultaneous Hayden expedition set off to uncover Yellowstone’ssecrets.
In their own ways, both would transform howhumankind saw this remote corner of Wyoming.
As Doane clambered back down Washburn Mountainthat hot day in 1870, he was heading back into a different world.
When the Hayden expedition returned, it wouldbe with photographs and paintings of Yellowstone that would capture the public’s attention.
It would be off the back of these images thatCongress acted, passing a bill signed into law on March 1, 1872, that made Yellowstoneone of the very first national parks in the world – possibly the very first (there’sa contender in Mongolia that may have pipped it to the post).
But it would be Doane who eventually madethe most intriguing contribution.
The idea of a vast, dead volcano underneathYellowstone lingered in the imagination.
For a long time – almost 8 decades in fact- it was part of the lore of the park.
But then, at some point in the mid-20th century, people decided to check if the volcano really was as dead as Doane had claimed.
What they eventually found would explode everythingAmerica thought it knew about its favorite park.
The Volcano Made Visible The fact that we ever discovered the truthabout Yellowstone is down almost entirely to two things: a lump of rock, and a disappointingboat trip.
Let’s start with the rock first.
In the late 1950s, a Harvard grad studentnamed Francis “Joe” Boyd was poking around the park when he stumbled across somethingcalled a welded tuff.
Now, to you or me, a welded tuff would lookno different from any other lump of rock.
But Boyd was a geologist, and to him a weldedtuff didn’t look like random rock.
It looked like what it was: ash that had oncebeen burning hot before becoming compressed and solidifying.
It also looked like something that had comefrom a geologically recent eruption.
But one rock, no matter how weird, does nota theory prove.
Even as two more welded tuffs were discoveredin Yellowstone park, the jury remained out.
It would take a weird boat trip to changethat.
Jump cut ahead to 1973.
Bob Smith, another geologist, was boatingacross Yellowstone Lake for some work when he came to an old dock.
A couple of decades before, Smith had mooredhis boat at this same dock, but now it was underwater and useless.
What’s more, the treeline was flooded outtoo.
Being far brainier than us, Smith didn’tjust shrug this off as a weird thing and carry on with his life.
Instead, he took a survey of the entire HaydenValley area, then compared it to data from 1923.
What he found was jaw-dropping.
The north end of Yellowstone Lake had risennearly 75cm, sending extra water flooding down the southern end and submerging the olddock.
There was only one reason the ground mightswell upwards like this.
The volcano beneath Yellowstone must stillbe alive.
Smith’s findings caused a minor sensation.
It helped that Smith was good at turning aphrase, such as when he described Yellowstone as a “living, breathing caldera”.
But it also helped that the park kept on doingweird things.
In the mid-1980s, there was a cluster of earthquakes, after which the the ground settled back down again to the height it had been in 1923.
Whatever was down there was like some greatbeast, a modern Cthulhu, dreaming in his layer at R'lyeh.
The only question was, what would happen whenit woke up? Over the next couple of decades, geologists, volcanologists, and lots of other people with jobs ending in “ologist” studied the heckout of Yellowstone.
It’s during this time that the giant magmaplume was discovered.
That the volcanic timeline from this video’sfirst section was pieced together.
Slowly, as the sheer size and power of theYellowstone volcano dawned, a term rose to describe it.
A term that started as strictly unscientific, but soon became so widely-used that science co-opted it: supervolcano.
Barely had the apocalyptic connotations ofthat term become clear when, in the mid-2000s, the ground started rising beneath YellowstoneLake again.
But if you’re expecting to hear that we’renow in the run up to an eruption… well, you’re about to be very disappointed.
It’s been estimated that the odds of Yellowstoneerupting in any year are about 0.
By way of comparison, it’s actually morelikely that another Chicxulub-sized asteroid will come slamming into Earth than it is thatYellowstone will blow its top in our lifetimes.
Even when it does finally blow again, theodds are even-slimmer that it’ll be a supereruption.
You may have seen claims that Yellowstoneerupts on a schedule and that we’re “overdue” another catastrophic eruption.
But volcanoes – with rare exceptions – simplydon’t work like that.
The boring truth is that Yellowstone probablywon’t go off for thousands more years and, when it does, it’ll likely be a lava flowthat’s destructive within the park itself, but barely noticeable for the world at large.
That being said, though, there is still thetiniest, tiniest chance that the big one really could happen.
And if it did… Well, let’s just say it’s time for thisvideo to take a turn into the speculative.
It’s time for us to witness America’sArmageddon.
The World on Fire Because no supervolcano has erupted in recordedhistory, we don’t really know what it would look like if Yellowstone suddenly went OldTestament on America’s ass.
But we can make some educated guesses.
For instance, it seems reasonable to assumethat the ground around Yellowstone Lake would start swelling again, doming upwards as magmarose into the chamber.
Quite possibly, this dome would rise on ascale we’ve never witnessed before.
With the ground heaving upwards, we’d startto get earthquakes, as the magma pushed solid rock out of its way to get to the surface.
The closer we got to lift-off, the shallowerthese earthquakes would get.
Pretty soon they’d likely be detected acrossthe entire park, along with a sharp and sudden increase in CO2.
In other words, we’d probably have somepretty distinct warning signs.
But that almost wouldn’t matter.
Because when the magma finally reached thesurface, we’d hit midnight on the doomsday clock.
Assuming an eruption as big as Yellowstone’slast supereruption, the effects would be devastating beyond belief.
Lava would inundate the park within a radiusof roughly 65km.
This would suck for campers, but the realproblem wouldn’t be on the ground.
It’d be in the air.
Thousands of cubic kilometers of volcanicash would be blasted high over Wyoming.
What happened next would depend a lot on thewind, but one likely outcome would be a layer almost a meter thick settling over most ofWyoming, Colorado, Montana, Idaho, and Utah.
This wouldn’t be like a layer of snow.
Just 30cm of ash can collapse a rooftop.
Every water supply it touched would be poisoned.
But it’s not like anyone would be aroundto worry about it, apart from a few unfortunate survivors.
Within 1, 000km of the blast, it’s estimatedthat 90 percent of people would be killed.
A quick, back of an envelope calculation putsthat at north of 10 million people dead.
And Yellowstone would just be getting started.
As the ash traveled, it would blanket theMidwest.
Not deep enough to crush buildings, but deepenough to cause large-scale crop failures and to make travel – and thus escape – animpossibility.
It would also be thick enough to cause majorrespiratory problems in anyone caught outside.
As the BBC once memorably put it: “Inhaled ash forms a cement-like mixturein human lungs.
By the time you reached the East Coast, theash layer would be a single centimeter thick.
Even at this thinness, though, it would badlydisrupt travel, which would in turn mess up supply chains.
Overall, its estimated that three quartersof the USA would be plunged into a deranged, post-apocalyptic fantasy.
And that would just be for starters.
Over the coming days, the ash from Yellowstonewould drift across the Atlantic, until it also coated Europe.
Remember the Icelandic eruption in April, 2010, that grounded every single plane on the continent? Well that would happen all over again.
While actual damage in Europe would be minimal, the economic cost would be enormous.
Finally, once three weeks had passed, thegasses unleashed into the atmosphere by Yellowstone would have completely shrouded the planet.
When Tambora erupted in 1815, causing theYear Without a Summer, it cooled the planet by something like 1.
A Yellowstone eruption, on the other hand, would cool the planet by up to 12 degrees C.
Nor would the effects only last a year.
Were Yellowstone to blow today, the 2020swould become known as the Decade without a summer.
Ten whole years in which every day was likea wet November in northern England.
Crops would fail.
The Monsoon would be disrupted, causing mass-starvationin Asia.
When the aftereffects finally faded, the sunwould shine back down on a planet – on a human civilization – that had been irrevocably changed.
But it would also shine down on a human racethat was still alive.
Yep, it would be a decade of catastrophe, misery, and really awful experiences, but it wouldn’t be the end of the world.
It’s not even a sure bet that it would bethe end of the USA.
Back in the Cold War, government scientistsestimated that losing a quarter of America’s population in a nuclear exchange still wouldn’tbe enough to destroy the United States as a political entity.
In the aftermath of a Yellowstone supereruption, the US would slowly, surely, rebuild from its Armageddon.
It might take decades.
It might take centuries.
But, in the end, the most-devastating eruptionin human history would fade into memory just as surely as the Black Death or NapoleonicWars.
But this most probably won’t happen.
As the American continent continues to movesouthwest, the magma chamber has found itself no longer under Yellowstone’s thin Basincrust, but under the thicker crust of the Rockies.
This could be enough to keep the supervolcanobottled up now forever.
So that’s it then, the history of both YellowstonePark, and the volcano sleeping beneath it.
The volcano that will almost certainly neverblow.
But if you do one day find yourself in northwestWyoming, and hear reports about the ground rising up wildly… and earthquakes gettingshallower and shallower… and CO2 escaping across the park… Then don’t run.
Just close your eyes, cross your fingers, and pray.
Because if the big one is coming – and that’sstill a pretty big if – there’ll be nothing else that you can possibly do.