The Earthquake Swarm At Yellowstone Is Going On A Lot Longer Than Expected


Robin Andrews

Science & Policy Writer


No reason to panic just yet, dear readers. Brian Matis/Shutterstock

Last week, we noted that there had been 30 closely-spaced earthquakes in one corner of Yellowstone National Park since June 12. While in itself this isn’t unusual, there was also a rather powerful 4.5M quake in the region – the most energetic since 2014, in fact.

At the time, there was nothing to worry about. Earthquakes swarms usually indicate either magma moving through the crust or the surrounding rock cracking or faulting slightly, which is to be expected around one of the world’s sleeping “supervolcanoes”.


However, that earthquake swarm hasn’t stopped yet, and as of Friday, June 23, there have been at least 769. By now, it’s likely to have risen to above 800.

Normally, earthquake swarms in areas like this contain 10 to 50 quakes, perhaps even as many as 100. This swarm has at 8-10 times the usual amount, and featured a bizarrely powerful one at its peak. So should we all start panicking now and run for the hills – or get into our doomsday bunkers?


Not really, we’re happy to report. Of course, Yellowstone could suddenly erupt today and we’d have egg on our faces – as well as a lot of volcanic ash – but the odds of it erupting this year still stand at 1-in-730,000. You’re about 146 times more likely to be killed in a car crash on any average day, so we’d worry more about remembering your seatbelt than a supervolcanic eruption.

The earthquake swarm – which is beginning to slow down a little – is centered on the border between Montana and northwestern Wyoming. Although we suggested it could be magma migrating through the crust, there is a minor fault running through this area, and it’s more likely that it’s slipping, causing the tremors.


There are no warning signs coming from the United States Geological Survey (USGS), who as of June 19 declared that things were normal in the region, both seismologically and volcanologically speaking. Earthquake swarms are indeed common in the area, and this one isn’t even that unusual.

The earthquake swarm has been centered on a minor fault line running through Yellowstone. USGS

As noted by the Idaho State Journal, the largest earthquake swarm took place in 1985, when more than 3,000 individual tremors took place in just three months in the exact same region of the park.

The media loves a good Yellowstone story though, because the idea of an impending supereruption is as terrifying as it is attention-grabbing – but rest assured, the world isn’t about to end.

Mind you, when Yellowstone eventually does erupt, it will be nothing less than a catastrophe. Hundreds of thousands would perish in the immediate aftermath, the global economy would crash spectacularly, and the planet would likely experience a volcanic winter – and it’s still not the most dangerous supervolcano on the planet.


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