Slumbering five miles beneath the surface of Yellowstone National Park in Wyoming is a timebomb more than 640,000 years in the making.
The Yellowstone supervolcano is a vast reservoir of magma with the potential to unleash a category eight eruption over 100 times more powerful than Krakatoa.
Thankfully, Yellowstone or any supervolcano of its size has never erupted within recorded human history.
But now, artificial intelligence (AI) reveals exactly what that would look like.
With Google’s ImageFX AI image generator, MailOnline has used the latest scientific research to predict how major cities would be affected by the eruption.
While the blast would kill thousands and send rivers of molten lava pouring up to 40 miles (64km) from the eruption site, this would only be the start of the devastation.
Experts predict that every town in a 50-mile (80km) radius would be all but annihilated by the same pyroclastic flows that created the petrified figures of Pompeii.
Meanwhile, the United States would be blanketed in a thick layer of choking ash as the world plunges into a volcanic winter which could last for years.
If the Yellowstone Supervolcano were to erupt, the devastation would cover almost the entirety of the United States. Spreading destruction through major cities and plunging the world into a volcanic winter. Now, AI shows what that might look like
Towns near Yellowstone would be instantly incinerated
A supereruption is defined as anything which reaches category eight or more on the Volcanic Explosivity Index in which at least 240 cubic miles (1,000 km) of material is ejected.
In Earth’s history, events on this scale have only occurred on a handful of occasions.
Yellowstone itself produced three supereruptions 2.1 million years ago, 1.3 million years ago, and 664,000 years ago.
Professor Tamsin Mather, an earth scientist from the University of Oxford, told MailOnline: ‘We haven’t seen one of these events in the modern historical or scientific era so there are lots of unknowns about what would happen.’
However, based on what was observed in the smaller eruptions of Mount Pinatubo in 1991 and Krakatoa in 1883, scientists can make some good assumptions.
Firstly, the most immediately devastating effects would be felt by the regions closest to the Yellowstone Caldera, a 43-by-28-mile-wide depression formed by previous eruptions.
It is thought that, were Yellowstone to erupt, the initial blast would release the energy of 875,000 megatons of TNT – more than 100 times the power of every nuclear bomb ever dropped.
The initial eruption would create a vast crater which would fill with lava over an area of around 40 miles (64km)
That initial blast would tear a vast crater into the ground and kill an estimated 90,000 people.
However, Yellowstone wouldn’t produce vast flows of lava right away.
Instead, most of the lava ejected onto the surface would fall back into the crater and spread no more than 40 miles (64km) at first.
Yet things might get significantly worse if the supereruption begins to form its own caldera.
Professor Mather says: ‘With these massive super volcanic eruptions they often form huge pits in the landscape as all the material empties out of the Earth’s crust to the point that it can’t support itself.
‘It’s like a piston. The Earth’s crust can collapse under its own weight and that could then push even more material out of the magma storage zone.’
Although the lava would be a deadly hazard, the worst danger for nearby towns would still be to come.
When eruptions begin, they often form what scientists call a ‘Plinian eruption column’, which is a tall pillar of ash and rock that punches up into the atmosphere before spreading out like an umbrella.
The true devastation would follow when pyroclastic flows, avalanches of boiling ash and rock, raced away from the volcano and incinerated nearby towns like West Yellowstone
This extremely heavy material is able to rise because it is hot enought to mix with the atmosphere and actually become buoyant.
But as the eruption continues, the volcano will often begin to eject more material at a faster rate.
‘It’s harder for that stuff to get buoyant because it has to mix with more atmosphere and be heated up,’ says Professor Mather.
‘What happens is that it passes a threshold where the eruption column collapses under its own weight and just falls down the sides of the volcano.’
These pyroclastic flows, or pyroclastic density currents, can travel at speeds of hundreds of metres per second and can travel tens to hundreds of miles from their source.
Made up of chunks of rock, dense ash, and searing gasses these flows race over the landscape destroying anything in their path.
Areas in their wake are covered with tens of metres of rock which welds solid due to the immense heat.
Worryingly for Yellowstone, Professor Mather points out that supervolcanoes seem to put out a greater proportion of their ejected material as pyroclastic flows.
Supervolcanoes produce more of their ejected material as pyroclastic flows, meaning towns tens or potentially hundreds of kilometres away could be affected
That means towns near the Yellowstone National Park such as West Yellowstone would be wiped from the map.
Cities across the US would be smothered in ash
For parts of North America which survived the initial blast, the next problem would be the vast clouds of ash produced by the eruption.
In addition to darkening the sky, this ash would soon start to fall all across the USA.
Simulations of a possible Yellowstone eruption show that the expanding ash cloud would be so powerful that it would actually outpace the prevailing winds for hours or even days.
That means almost the entire surface of North America would be blanketed by ash no matter which way the wind was blowing.
Studies suggest that ash could travel up to 932 miles (1,500 km) upwind, reaching as far as Miami and LA.
Cities within 311 miles (500km) of the eruption such as Casper, Wyoming and Billings, Montana could be covered with more than a metre (3ft) of ash.
Studies predict that the eruption could send ash up to 932 miles (1,500 km) upwind, reaching as far as Miami
Distant cities like LA would be plunged into darkness as ash filled the skies and would be coated with a few millimetres of volcanic ash
Meanwhile, cities in the Upper Midwest like Iowa, Minneapolis, and Minnesota would receive several centimetres.
Even cities as far from the eruption as Chicago, Seattle, and San Francisco could be coated with up to 3cm of ash.
If the eruption happened when the conditions were perfect, Professor Mather says London might even see some light ashfall.
Unlike the soft, light ash you might see in a fire, volcanic ash is a sharp, heavy mixture of rock and splintered volcanic glass.
This mixture is so dense that even small amounts building up on roofs can cause buildings to collapse.
Through the US’s agricultural heartlands of the Midwest, this ash would smother crops and destroy farms.
That devastation would send shockwaves rippling around the world even to countries which were physically unaffected.
Professor Mather says: ‘With our kind of present-day interconnected supply chain-based society it actually could have more effects [than previous supervolcanoes].
In Chicago, the city could be covered with as much as 3cm of ash. Even small amounts of ash are heavy enough to damage electrical equipment and cause weak structures to collapse
Cities closer to the eruption such as Montana or Billings would be covered with up to a metre of ash. This would collapse many buildings and cause massive disruption
‘If Yellowstone went off and really hit the North American economy very hard, a really massive eruption could have global ramifications.’
The entire globe would be plunged into a volcanic winter
However, the blast from the Yellowstone Supervolcano would be so strong that it affect every country on Earth for several years to come.
Alongside the huge clouds of ash, supervolcanoes also inject massive quantities of sulphur into the stratosphere, the part of the atmosphere containing the ozone layer.
In the air, that sulphur reacts with oxygen to create sulphur dioxide which spreads into a fine particle haze called an aerosol veil.
Professor Mather says: ‘That haziness reflects sunlight back into space. So, if you were a Martian, you’d see the planet get ever so slightly brighter.
‘What that does is cool the lower planet down.’
The exact amount that this would cool the planet is a matter of active scientific debate.
Throughout midwestern states like Idaho or Indiana, the ash coating would kill crops and destroy farms. Then, as the climate cools in the following years it would become even harder to grow food
Professor Mather says that some estimates suggest global cooling of around 5°C (9°F) for several years with temperatures potentially falling up to 10°C (18°F) in the first year.
A recent pre-print study conducted by the Arctic University of Norway suggests that the maximum cooling a volcanic event could produce is 12°C (21.6°F).
If that were the case, countries around the world could experience exceptionally cold winters and could face widespread crop shortages as harvests failed.
However, the actual pattern of global cooling is likely to affect regions in different ways.
Studies also show that northern latitudes might actually see summer cooling paired with warmer winters due to disruption to the Gulf Stream.
Professor Mather says: ‘There isn’t evidence yet that it tips us into a new ice age, but I think the evidence is that we could certainly feel some quite meaty effects for a few years.’
Likewise, some researchers also argue that the actual cooling effect might be smaller than anticipated.
By studying tree rings, Dr Zachary McGraw of Columbia University found that even a large eruption might not cause that much cooling.
In the UK, cities like London (pictured) would likely experience its coldest summer temperatures since the 1816 ‘Year Without a Summer’ as sulphur in the atmosphere reflects heat back out to space. The ash would also cause notably beautiful and intense sunsets
Dr McGraw told MailOnline: ‘The relatively modest cooling that followed the largest eruption in tree ring temperature reconstructions, the Mt Samalas eruption in 1257 AD, suggests that even larger eruptions like Yellowstone may be unlikely to cause strong cooling.’
Dr McGraw adds that ‘theories of extreme global impacts have already been largely debunked.’
In a paper published last year, Dr McGraw and his co-authors predict that cooling from Yellowstone probably would not exceed 2.7°C (4.86°F).
However, even a small change in global temperature can and has led to catastrophic consequences.
Following the eruption of Mount Tambora in 1815, global temperatures fell between 0.4 and 0.7 °C (0.7–1 °F).
The following year, Europe experienced the so-called ‘Year Without a Summer’ and was hit by the summer temperatures recorded between 1766 and 2000.
This led to widespread crop failure and major food shortages across the Northern Hemisphere, especially in Europe, which was still recovering from the Napoleonic Wars.
If even relatively small levels of summer cooling on this scale occurred after ash destroyed much of America’s agricultural capacity, the results could be even more disastrous.
COULD AN ERUPTION AT THE YELLOWSTONE SUPERVOLCANO BE PREVENTED?
Recent research found a small magma chamber, known as the upper-crustal magma reservoir, beneath the surface
Nasa believes drilling up to six miles (10km) down into the supervolcano beneath Yellowstone National Park to pump in water at high pressure could cool it.
Despite the fact that the mission would cost $3.46 billion (£2.63 billion), Nasa considers it ‘the most viable solution.’
Using the heat as a resource also poses an opportunity to pay for plan – it could be used to create a geothermal plant, which generates electric power at extremely competitive prices of around $0.10 (£0.08) per kWh.
But this method of subduing a supervolcano has the potential to backfire and trigger the supervolcanic eruption Nasa is trying to prevent.
‘Drilling into the top of the magma chamber ‘would be very risky;’ however, carefully drilling from the lower sides could work.
This USGS graphic shows how a ‘super eruption’ of the molten lava under Yellowstone National Park would spread ash across the United States
Even besides the potential devastating risks, the plan to cool Yellowstone with drilling is not simple.
Doing so would be an excruciatingly slow process that one happen at the rate of one metre a year, meaning it would take tens of thousands of years to cool it completely.
And still, there wouldn’t be a guarantee it would be successful for at least hundreds or possibly thousands of years.
