Yellowstone's Supervolcano Is Literally Changing Shape - But Why?

Don't panic. Or do, we can't really stop you. Suzi Pratt/Shutterstock

Once again, let’s get this out of the way right at the start: Yellowstone supervolcano is not about to catastrophically erupt. If it did, it would likely be a very limited lava flow which would probably kill a total of zero people. In any case, the chance of any major eruption happening this year is roughly one-in-730,000.

That said, a new ground deformation map of the famous National Park is doing the rounds online, and as ever, it’s understandably causing a bit of a stir.

The map, by the United States Geological Survey (USGS), reveals that the terrain around the volcanic cauldron (caldera) has indeed been shifting over the past couple of years. The soil above Yellowstone’s Norris Geyser Basin has moved up by 7 centimeters (around 3 inches) in that time period, and within the heart of the caldera itself, the ground has dropped by 3 centimeters (1.2 inches).

So what’s going on down below? First off, the ground around Yellowstone caldera, like plenty of active volcanic systems around the world, is always moving to some degree. In fact, this recent deformation – which was mostly calculated using radar technology – is comparable to Yellowstone’s activity just a few decades earlier.

The uplift at Yellowstone between 2015 and 2017. The redder the color, the greater the rate of uplift. Fault lines are shown in black. Chuck Wicks/USGS

For example, between 1997 and 2003, the ground in the caldera rose by 12 centimeters (5 inches), whereas parts of Yellowstone Lake sank by 4 centimeters (1.6 inches). Similar patterns have been seen during the 1970s and 1980s, and if you hadn’t already noticed, there was no single eruptive event at Yellowstone during that time.

So what’s causing the deformation? Well, it could be a range of things, but none of them are anything to be concerned about at present.

Yellowstone caldera is a dormant volcano with a very active volcanic system operating beneath it. As well as having a series of magma chambers filling up beneath it, it is also a landscape riddled with fault lines that slip and shift on occasion.

Hydrothermal fluids – superheated water-rich liquids driven by the heat of the magma – are also zipping through the subterranean landscape, and occasionally make their way to the surface in the form of geysers and hot springs.

All three of these are likely responsible for the changes in local topology.

Unless the core of Yellowstone suddenly rises up to become a veritable hill, and unless parts of the National Park start exploding and melting, there is really nothing to worry about. As the USGS are keen to point out, activity at the famous volcano is still in the normal range.

At the same time, the earthquake swarm that’s still taking place at Yellowstone – now numbering in the 1500 range – is also not worth losing sleep over.

Although the frequency of the quakes is slightly above expected background levels, swarms like this are typically triggered by the same movement of high-pressure subterranean fluids beneath the surface. It’s just the Earth flexing its muscles.

If you’re still worried about all this, then why not take a look at Campi Flegrei, the Italian supervolcano which is, arguably, the most dangerous supervolcano in the world today. Between 1982 and 1984, the ground there rose by 1.8 meters (5.9 feet) – something which frightened volcanologists at the time – and yet nothing happened.

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The most dangerous thing about Yellowstone is, and will be for some time, human error. Somehow, despite clear warnings not to go too close to them, people keep falling into the park’s hot springs – and these spontaneous acidic baths result in their complete dissolution within a single day.

Forget supereruptions. It’s human silliness you should be worried about.

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