Throughout most of its life, Yellowstone has featured extensive lava flows and, more commonly, hydrothermal blasts. Any subsequent eruption is far more likely to be manifested in this way, not a supervolcanic eruption.
Yellowstone’s a supervolcano, sure, but it’s a bit like an Olympic medal: just because you erupted madly once or twice, doesn’t mean you can again.
In fact, it can’t, at the moment. Magma reservoirs need to be around 50 percent molten in order to trigger an eruption. Right now, Yellowstone’s magma reservoirs are at most 15 percent molten. So no end-of-days for you, dear readers. In terms of an eruption risk, you’re about as likely to be killed by it as that fake supervolcano that Fox News “discovered” in Vermont recently.
Yellowstone is an active volcanic center. You should expect things like earthquake swarms and ground deformation from time to time. It’s the reason you have such stunning – and deadly, if you’re clumsy – geothermal features peppered around the National Park too: there’s a potent heat source down there.
A crack, however, doesn’t in any way suggest an eruption is imminent. Sadly, though, those at the Yellowstone Volcano Observatory (YVO) always get a huge uptick in emails from worried members of the public every time a new rumor goes around, which is why for something this innocuous, I won’t even bother winging them a communique myself.
It cannot be stressed enough that the risk of an eruption at Yellowstone of any kind is magnitudes lower than you think. The USGS is on the case, and they’d be the first to let the public know if something was genuinely amiss.