No, the Yellowstone supervolcano is not ‘overdue’

Why mega-eruptions like the ones that covered North America in ash are the least of your worries.

Ash deposits of some of North America's largest volcanic eruptions.

Ash deposits of some of North America's largest volcanic eruptions.

Image: USGS - public domain
  • The supervolcano under Yellowstone produced three massive eruptions over the past few million years.
  • Each eruption covered much of what is now the western United States in an ash layer several feet deep.
  • The last eruption was 640,000 years ago, but that doesn't mean the next eruption is overdue.

The end of the world as we know it

\u200bHeinrich Berann's panoramic view of Yellowstone National Park

Panoramic view of Yellowstone National Park

Image: Heinrich Berann for the National Park Service – public domain

Of the many freak ways to shuffle off this mortal coil – lightning strikes, shark bites, falling pianos – here's one you can safely scratch off your worry list: an outbreak of the Yellowstone supervolcano.

As the map below shows, previous eruptions at Yellowstone were so massive that the ash fall covered most of what is now the western United States. A similar event today would not only claim countless lives directly, but also create enough subsidiary disruption to kill off global civilisation as we know it. A relatively recent eruption of the Toba supervolcano in Indonesia may have come close to killing off the human species (see further below).

However, just because a scenario is grim does not mean that it is likely (insert topical political joke here). In this case, the doom mongers claiming an eruption is 'overdue' are wrong. Yellowstone is not a library book or an oil change. Just because the previous mega-eruption happened long ago doesn't mean the next one is imminent.

Ash beds of North America

Ash beds deposited by major volcanic eruptions in North America.

Ash beds deposited by major volcanic eruptions in North America.

Image: USGS – public domain

This map shows the location of the Yellowstone plateau and the ash beds deposited by its three most recent major outbreaks, plus two other eruptions – one similarly massive, the other the most recent one in North America.

Huckleberry Ridge

The Huckleberry Ridge eruption occurred 2.1 million years ago. It ejected 2,450 km3 (588 cubic miles) of material, making it the largest known eruption in Yellowstone's history and in fact the largest eruption in North America in the past few million years.

This is the oldest of the three most recent caldera-forming eruptions of the Yellowstone hotspot. It created the Island Park Caldera, which lies partially in Yellowstone National Park, Wyoming and westward into Idaho. Ash from this eruption covered an area from southern California to North Dakota, and southern Idaho to northern Texas.

Mesa Falls

About 1.3 million years ago, the Mesa Falls eruption ejected 280 km3 (67 cubic miles) of material and created the Henry's Fork Caldera, located in Idaho, west of Yellowstone.

It was the smallest of the three major Yellowstone eruptions, both in terms of material ejected and area covered: 'only' most of present-day Wyoming, Colorado, Kansas and Nebraska, and about half of South Dakota.

Lava Creek

The Lava Creek eruption was the most recent major eruption of Yellowstone: about 640,000 years ago. It was the second-largest eruption in North America in the past few million years, creating the Yellowstone Caldera.

It ejected only about 1,000 km3 (240 cubic miles) of material, i.e. less than half of the Huckleberry Ridge eruption. However, its debris is spread out over a significantly wider area: basically, Huckleberry Ridge plus larger slices of both Canada and Mexico, plus most of Texas, Louisiana, Arkansas, and Missouri.

Long Valley

This eruption occurred about 760,000 years ago. It was centered on southern California, where it created the Long Valley Caldera, and spewed out 580 km3 (139 cubic miles) of material. This makes it North America's third-largest eruption of the past few million years.

The material ejected by this eruption is known as the Bishop ash bed, and covers the central and western parts of the Lava Creek ash bed.

Mount St Helens

The eruption of Mount St Helens in 1980 was the deadliest and most destructive volcanic event in U.S. history: it created a mile-wide crater, killed 57 people and created economic damage in the neighborhood of $1 billion.

Yet by Yellowstone standards, it was tiny: Mount St Helens only ejected 0.25 km3 (0.06 cubic miles) of material, most of the ash settling in a relatively narrow band across Washington State and Idaho. By comparison, the Lava Creek eruption left a large swathe of North America in up to two metres of debris.

The difference between quakes and faults

Comparison chart of eruption volumes

The volume of dense rock equivalent (DRE) ejected by the Huckleberry Ridge event dwarfs all other North American eruptions. It is itself overshadowed by the DRE ejected at the most recent eruption at Toba (present-day Indonesia). This was one of the largest known eruptions ever and a relatively recent one: only 75,000 years ago. It is thought to have caused a global volcanic winter which lasted up to a decade and may be responsible for the bottleneck in human evolution: around that time, the total human population suddenly and drastically plummeted to between 1,000 and 10,000 breeding pairs.

Image: USGS – public domain

So, what are the chances of something that massive happening anytime soon? The aforementioned mongers of doom often claim that major eruptions occur at intervals of 600,000 years and point out that the last one was 640,000 years ago. Except that (a) the first interval was about 200,000 years longer, (b) two intervals is not a lot to base a prediction on, and (c) those intervals don't really mean anything anyway. Not in the case of volcanic eruptions, at least.

Earthquakes can be 'overdue' because the stress on fault lines is built up consistently over long periods, which means quakes can be predicted with a relative degree of accuracy. But this is not how volcanoes behave. They do not accumulate magma at constant rates. And the subterranean pressure that causes the magma to erupt does not follow a schedule.

What's more, previous super-eruptions do not necessarily imply future ones. Scientists are not convinced that there ever will be another big eruption at Yellowstone. Smaller eruptions, however, are much likelier. Since the Lava Creek eruption, there have been about 30 smaller outbreaks at Yellowstone, the last lava flow being about 70,000 years ago.

As for the immediate future (give or take a century): the magma chamber beneath Yellowstone is only 5 percent to 15 percent molten. Most scientists agree that is as un-alarming as it sounds. And that its statistically more relevant to worry about death by lightning, shark, or piano.

Strange Maps #1041

    Got a strange map? Let me know at strangemaps@gmail.com.

    Live on Monday: Does the US need one billion people?

    What would happen if you tripled the US population? Join Matthew Yglesias and Charles Duhigg at 1pm ET on Monday, September 28.

    ‘Time is elastic’: Why time passes faster atop a mountain than at sea level

    The idea of 'absolute time' is an illusion. Physics and subjective experience reveal why.

    ESA
    Surprising Science
    • Since Einstein posited his theory of general relativity, we've understood that gravity has the power to warp space and time.
    • This "time dilation" effect occurs even at small levels.
    • Outside of physics, we experience distortions in how we perceive time — sometimes to a startling extent.
    Keep reading Show less

    Learn innovation with 3-star Michelin chef Dominique Crenn

    Dominique Crenn, the only female chef in America with three Michelin stars, joins Big Think Live.

    Big Think LIVE

    Having been exposed to mavericks in the French culinary world at a young age, three-star Michelin chef Dominique Crenn made it her mission to cook in a way that is not only delicious and elegant, but also expressive, memorable, and true to her experience.

    Keep reading Show less

    Universe works like a cosmological neural network, argues new paper

    Controversial physics theory says reality around us behaves like a computer neural network.

    Synapses in space.

    Credit: sakkmesterke
    Surprising Science
    • Physicist proposes that the universe behaves like an artificial neural network.
    • The scientist's new paper seeks to reconcile classical physics and quantum mechanics.
    • The theory claims that natural selection produces both atoms and "observers".
    Keep reading Show less

    We studied what happens when guys add their cats to their dating app profiles

    43% of people think they can get a sense of someone's personality by their picture.

    Photo by Luigi Pozzoli on Unsplash
    Sex & Relationships

    If you've used a dating app, you'll know the importance of choosing good profile pics.

    Keep reading Show less
    Coronavirus

    Quarantine rule breakers in 17th-century Italy partied all night – and some clergy condemned the feasting

    17th-century outbreaks of plague in Italy reveal both tensions between religious and public health authorities.

    Scroll down to load more…
    Quantcast