What If Yellowstone Did Erupt?

Are you one of those people who like to play “what if” games? You know who you are, posing the tough questions like, “What if the world suddenly stopped rotating on its axis?” (We’d all fly off into space due to no more gravity holding us onto the earth’s surface. But don’t worry. This is highly unlikely ever to happen.)

Survivalists typically love this past time and use the ideas produced by planning out obscure scenarios to prepare mentally for unforeseen happenstances – and for fun.

News articles appear in the mainstream media periodically about the calculated consequences of the Yellowstone National Park supervolcano erupting. It’s important to keep in mind that this line of speculation is merely that: speculation, also called “guessing.”

Many people remember when Mount St. Helens erupted in western Washington state at 8:32 AM Sunday, May 18, 1980. Fifty-seven people lost their lives as a result of the sudden, unexpected volcanic activity.

The force of that recent eruption blasted debris over 229 square miles and destroyed timber valued at several million dollars, making Mount St. Helens the deadliest and most financially destructive volcanic event in the history of the United States.

The supervolcano at Yellowstone in Wyoming has the potential to make Mount St. Helens look like a geological sneeze. The entire National Park sits on top of an active, seething, subterranean cauldron of hot magma itching to escape.

Those beautiful bubbling geysers and hot springs which are the hallmark of any Yellowstone visitor’s experience are the natural signs of volcanic activity beneath the earth’s surface.

Yellowstone is termed a “supervolcano” rather than an ordinary old volcano. What’s the difference?

The answer is expressed in orders of magnitude (severity) taken from the Volcano Explosivity Index (VEI) which is a real thing. Any volcanic eruption that spews more than 250 cubic miles of magma is deemed a supervolcano.

Did you know that the geologic record shows that Yellowstone has witnessed three of these extraordinary explosions? It’s true but not many people know that the first such event happened about 2.1 million years ago, repeated 1.2 million years, and once again 640,000 years ago.

Compared to Mount St. Helens, these long-ago Yellowstone eruptions were approximately 6,000, 700, and 2,500 times more powerful, respectively.

After the most recent eruption, the area around the volcanic epicenter collapsed in on itself which produced the vast sunken crater (caldera) which today measures 1,500 square miles.

It is the residual heat from that eruption 640,000 years ago that literally fires Yellowstone’s signature hot springs and geysers.

Computers are great for modeling “what-if” scenarios based on known data. Scientists have run simulations to see how bad life around Wyoming would be if Yellowstone let loose again. The picture is not pretty.

We could reasonably expect ashfall thousands of miles away from the center of the eruption. This happened after the Mt. Saint Helens eruption. In 1985, I happened to be driving west on I-90 somewhere in the wilds of Montana. Suddenly, the ground on either side of the highway turned a white-gray color, as far as the eye could see.

Thinking it was the wrong season for snow, I stopped my car and got out to take a closer look. Lo and behold, the strange substance was finely powdered ash from the 1980 Washington eruption. A strange feeling overtook me – “This is something unique and historical,” I thought – so I filled several small bottles I had with me with the historical ashes.

Volcanic ash hangs around for years after a large eruption, blanketing the earth below and adding particulate matter to the skies above. This ash is full of poisons and definitely sets back agricultural activities.

Experts in these matters believe that a massive Yellowstone super-eruption would damage buildings and shut down power plants.

Before going any further, it bears mentioning that no expert knows for sure when any particular volcano will erupt, including Yellowstone. Remember that we’re still playing the “what if” game.

That said, in 2014, a group of scientists modeled the ash fall distribution from a Yellowstone supereruption and presented their findings of Geochemistry, Geophysics, Geosystems.

Fasten your seat belts for these projections: large areas in Wyoming, Montana, Idaho, Colorado, and Utah would be buried in three feet of toxic volcanic ash – which is actually a combination of shattered rock and the glass by-product of vulcanization (extremely high heat and pressure).

Say good-bye to living plants and animals, building roofs, and a myriad of electrical equipment covered by this inevitable ashfall.

Jacob Lowenstern, one of the theoretical researchers, hastened to add that his team’s findings were in no way, shape or form, an actual prediction. These folks were simply playing “what if?”

“Even if Yellowstone did erupt again, you probably wouldn’t get that worst-case scenario,” Lowenstern explained. “What’s much, much more common are small eruptions — that’s a point that often gets ignored in the press.”

Lowenstern should know. He is the chief scientist at the Yellowstone Volcano Observatory which is located in Menlo Park, California.

If it makes you feel any better, earth scientists have identified at least 47 supervolcanic eruptions since the Earth was formed. The most recent happened about 26,000 years ago in New Zealand, near Lake Taupo.

Geologists think that multiple, clustered, smaller eruptions would produce lava flows and release much of the subterranean pressure which builds up until it seeks release above ground through volcanic vents to the open air or water.

Any Yellowstone eruption under those circumstances would probably have a reduced force much like other recorded volcanos. The lava would probably flow no further than 40 miles or so from the volcanic center and stay within the National Park boundaries. Only about a third of the ejected material would wind up in the atmosphere.

In geological terms, that’s the good news. The bad news is that the ashfall would destroy life as we know it for miles in an umbrella pattern radiating out from the main volcano in all directions.

Due to the sudden catapulting of volcanic debris into the atmosphere, Earth’s weather would change dramatically, if for a fairly short time. The sulfur aerosols emitted would reflect sunlight back into the atmosphere, reducing global temperatures.

Seismographs would herald a supervolcanic eruption, the experts say. As Lowenstern put it, “We’d likely first see intense seismic activity across the entire park.”

Presumably, humans in the surrounding areas would have weeks, if not months, to evacuate out of harm’s way.