I get asked about Yellowstone at least a few times a month. It's almost never a question about the gorgeous geysers, hot springs, mud pots, or other hydrothermal features. People don't even ask me where the Yellowstone hotspot was hanging out before it got to Wyoming (I'm going to tell you about it in an upcoming post, though!). The questions I get most frequently about America's most famous volcanic National Park are these:
1. Is Yellowstone going to erupt soon?
2. When it does, will it destroy civilization?
Those questions honestly make me sad, because there's so much exciting stuff about it, and it all gets buried under a metric crapton of sensationalism and misinformation, delivered near daily by various press outlets and television specials. Has Yellowstone experienced enormous eruptions in the past? It definitely has, repeatedly. Will it erupt on those huge scales again? Quite possibly! But we're going to see why the volcanologists at Yellowstone Volcano Observatory aren't placing their bets on a Big One happening any time soon (even on a geologic timescale), and why civilization as a whole will probably survive the blast even if it does.
If you decide not to read on and just want the quick answers, here's the tl;dr:
1. Yes, it will! But the next eruption is likely to be pretty small, just a bit of lava extruding with maybe minor amounts of ash. And with all of the equipment we've got the volcano wired with, we'll have ample notice.
2. If the next enormous eruption happens in our lifetimes, there will of course be death and destruction, but not enough to destroy the United States, or even just the American West. Civilization as we know it will survive.
Sorry to disappoint.
The true story of Yellowstone isn't anywhere near as terrifying and dramatic as the breathless articles and dire documentaries would have you believe. But in the science world, reality rules. And it's not like an enormous caldera blown in the northwest corner of Wyoming, sitting atop a large and active magma chamber, filled with hydrothermal activity, can in any way be boring! Let's adjust our expectations and set some rumors to rest.
Isn't Yellowstone overdue for an eruption?
Most definitely not:
In terms of large explosions, Yellowstone has experienced three -- at 2.08, 1.3, and 0.631 million years ago. This comes out to an average of about 725,000 years between eruptions. That being the case, we still have about 100,000 years to go, but this number is based on very little data and so is basically meaningless (would you base any conclusion on the average of just two numbers?). The point, however, is that if someone, or some article or documentary, says that Yellowstone erupts every 600,000 years, you know right off the bat that they are full of baloney....
With rare exceptions, volcanoes do not accumulate magma at a constant rate (in the few cases where that does happen, eruptions can be somewhat regular). Instead, volcanoes erupt when there is a sufficient supply of liquid magma in the subsurface and sufficient pressure to cause that magma to ascend to the surface. This does not generally happen on a schedule.
Okay, but, when it does go, it'll wipe out humanity, or at least most of North America, right?
I know, I know, you're really hoping for something epic disaster-movie worthy, but I'm afraid the science says...
YVO gets a lot of questions about the potential for Yellowstone, or some other caldera system, to end all life on Earth. So, we'll answer that question right off the bat—no, a large explosive eruption at Yellowstone will not lead to the end of the human race (most Yellowstone eruptions do not fit this worst-case scenario anyhow, but rather are lava flows). The aftermath of such an explosion wouldn't be pleasant, certainly, but we won't go extinct. How do we know? Because this "super eruption" experiment has already been run. Twice!
But it has to be dangerous! People wouldn't make such a big deal out of it if it wasn't!
Correct! Yellowstone may not be a human-species ender, but that doesn't mean it's not hazardous! Hazards abound, and the good people at YVO are keeping a close eye on them. Number 2 on this list will definitely surprise you!
News articles, websites, and videos often exaggerate the rarest events, while ignoring hazards that may actually happen during a person's life. So right here, right now, we're going to flip this around and discuss Yellowstone's geologic hazard scenarios in order from most to least likely
Okay, but, surely, Yellowstone's at the top of the list when it comes to the most dangerous volcanoes in the United States, right?
Alas, no. It's not.
You know it kills me to disappoint you, right?
The overall threat score is determined by multiplying the sum of the hazard factors by the sum of the exposure factors. The top three volcanoes, in order, are Kilauea (Hawaii), Mount St. Helens (Washington), and Mount Rainier (Washington). A general categorization was also introduced – "very high threat," "high threat," "moderate threat," "low threat," and "very low threat."In 2005, Yellowstone was ranked #21 in the threat assessment. Now for the big reveal…in 2018…Yellowstone was ranked…#21! This qualifies Yellowstone as a "high threat" volcanic system. This is not a change or any sort of upgrade in the threat posed by Yellowstone, and carries no implications for future eruptive activity. It is merely a way to provide a sense of Yellowstone's threat level compared to other volcanoes in the USA.
Relative to the other US calderas, Yellowstone lies in the middle. Long Valley caldera is #18 ("very high threat") and Valles caldera is #68 ("moderate threat").
Please say it's a supervolcano. Please.
I'm so sorry.
But if it's any consolation, you can call any eruption VEI 8 or greater a super eruption!
I have a confession to make. I really don't like the term "supervolcano." And I'd like to use this week's edition of Yellowstone Caldera Chronicles to rant about the topic. I'd also like to propose that we use a different term.
I know. Reality doesn't always live up to the hype - especially when some individuals and publications like to... how to put this delicately... lie like bad carpets in order to get attention. Check out some of the nonsense YVO has to put up with!
Wait - won't earthquakes on the Ring of Fire trigger eruptions?!
I'm just going to stand aside and let this headline say the needful:
Basically: rumors of Yellowstone's impending catastrophic mega-eruption have been exponentially exaggerated. Don't fall for the hype. Plan your visit to the national park without a single fear that the entire place will suddenly erupt in a volcanic cataclysm worthy of the most overblown tabloid imagining. Live in the area without worrying about being enveloped in an unexpected pyroclastic flow. The staff at Yellowstone Volcano Observatory are paying strict attention, and will be able to give you plenty of advance notice when the magma chamber fills to super eruption capacity.
Meanwhile, enjoy some of the best active hydrothermal features on the planet!