Yellowstone National Park is a place of beauty and serenity that draws millions of people every year. From Old Faithful to the over 2 million acres of pristine wilderness, Yellowstone is an American icon for the ideal family vacation. But there is a Potential Disaster lurking beneath the casual visitors’ view, and we aren’t talking about grizzly bears. 
Yellowstone National Park sits directly above a volcano that is more than 1000 times more powerful than Mount Saint Helen. To put this perspective, the 1980 eruption of Mount Saint Helen created a crater that is 2 square miles. The Yellowstone caldera is 1477 square miles, almost half of Yellowstone National Park. Yellowstone is sometimes called a “Super-Volcano” which is an unofficial term that is generally defined as a VEI 8 or higher. The VEI (Volcanic Explosivity Index) is a system that ranks volcanic eruptions based on how powerful they are, each level being 10 times more powerful than the previous level. For example, the Eyjafjallajökull eruption in Iceland in May of 2010 was a VEI 4 and the Kakatoa eruption of 1815 was a VEI 6. Therefore, the Krakatau eruption was about 100 times more powerful than the Eyjafjallajökull eruption.
There are 7 known super-volcanoes in the world:
Lake Toba in Indonesia Aira Caldera in Japan
Long Valley Caldera in California
Lake Taupo in New Zealand
Valles Caldera in New Mexico
Siberian Traps in Russia
Yellowstone Caldera in Wyoming
Humans have only experienced one super-volcanic eruption in their long history, that of Lake Toba about 74,000 years ago. The good news is that obviously the human race survived it. The bad news is that we almost didn’t.
This eruption of Lake Toba sent so much ash into the atmosphere that it blocked out the sun worldwide, sending the Earth into a volcanic winter that lasted as long as a decade and was followed by a small ice age that lasted a millennia. Global temperatures dropped by as much as 59 degrees Fahrenheit and the rain became black and acidic due to materials released by the volcano. 75 percent of all plant life in the northern hemisphere died and some scientists speculate that as much as 90 percent of the human population died, leaving only 1,000 females capable of procreating. Luckily for us, Yellowstone has never had an eruption as destructive as Lake Toba. But it’s close.
The Yellowstone Hot Spot has had over 140 eruptions in the last 17 million years. The frequency of these eruptions has changed over time as follows:
Prior to 15.2 million years ago | 30 eruptions per million years |
15.2 million years ago to 8.5 million years ago | 20-30 eruptions per million years |
8.5 million years ago to present | 2-3 eruptions per million years |
So, what would a modern day super-eruption of Yellowstone be like for the inhabitants of Earth? To put it lightly, really really bad. Everything within 65 miles would be killed within seconds by the pyroclaustic flow (a wave of superheated gas and rock that can reach temperatures of over 1800 degrees Fahrenheit and exceed 450 miles per hour.)
Anyone unfortunate enough to live within 500 miles of the eruption would be trapped by over 2 feet of ash within hours and forced to wait for the roof of their home to collapse on top of them.
For those who survive the actual eruption of Yellowstone, the struggle for life has only just begun.
Magma and other volcanic materials would shoot over 30 miles into the atmosphere. Volcanic ash could remain there for years, reflecting solar radiation back into space and causing global surface temperatures to drop by as much as 68 degrees Fahrenheit. Basically, it would be the decade (or longer) without a summer and we would enter an ice age.
The sun would be blocked out completely for months, leaving us in a seemingly never-ending midnight. The ash in the atmosphere would turn the rain acidic, poisoning the vegetation that somehow managed to survive, and this would continue for decades. Once the ash in the atmosphere began to dissipate, it would turn the sky a ghoulish red color and the sunlight would remain at a dusk-like luminosity for years. World-wide food supplies would be devastated, leading to extensive starvation.
Even after the sun began to shine and the growing season some-what returned, the ash covering the soil in North America would take decades to erode and even longer for the vegetation to recover. The entire United States would be covered by no less than 5 inches of volcanic ash (it takes only one millimeter to close an airport) and half of the country, including the Grain Belt and the Great Lakes, would receive no less than 3 feet of ash. This volcanic ash would poison any open fresh water supplies, such as lake reservoirs, and clog vehicle engines and other exposed electrical systems, such as power generators and radio transmitters. If someone was unfortunate enough to inhale it, the microscopic pumice particles would rip up their lungs, causing their lungs to start bleeding. The blood would mix with the volcanic ash to form a cement like substance, causing them to slowly asphyxiate.
We could reasonably expect as many as 5.874.000.000 (that’s almost 5.9 billion) people to die world-wide.
So now that I’ve scared the daylights out of you, let me say that most geologists are fairly certain that we are not in danger of an immediate eruption of Yellowstone. However, there are clues that an eruption might be nearing, such as increased frequency or magnitude of earthquakes, and ground swelling. While the number of earthquakes has remained relatively stable, albeit with temporary increased activity, the ground has been rising more or less since the first survey was taken in 1923.
1923-1984 | 36 inch rise cumulative |
1985-1992 | 6 inch drop cumulative |
1993-2003 | No data found |
2004-2006 | 2.8 inch rise per year |
2007-2010 | 1/3 inch rise per year |
Some scientists speculate that life on Earth is 5-10 times more likely to experience an “Super-Volcano” eruption than an asteroid impact. But you, personally, only have a 0.00014% chance of being alive when Yellowstone erupts.
Still, I wouldn’t worry too much. Mostly because there is absolutely nothing you can do to prevent it. Yellowstone will erupt again one day; it’s only a question of when.
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