It will be a disaster for the US, a near-apocalyptic catastrophe. There’s also a good chance that we’d lose a few years or decades of summer, as the sulfur particles emitted during the eruption will block out the Sun to some degree for as long as they linger in the once-blue skies.
However, as the USGS note, the last 20 eruptions have been lava effusions, which will only reach the boundaries of the National Park. In fact, the yearly probability of another caldera-forming eruption can be approximated as one in 730,000 or 0.00014 percent. That’s really quite low.
A super-eruption is likely to be tens of thousands of years away yet, and even a lava flow will not take place for several centuries. There’s just no sign that the magma chamber is restless right now – it’s still slowly just filling up, and biding its time.
Home of the Brave
The sky above supervolcanoes often turn red for days or weeks after they unleash their fury. R.T.Wohlstadter/Shutterstock
So what of the others?
Let’s stick to the US for now. The Long Valley Caldera “super-erupted” and formed its caldera 760,000 years ago. It was less powerful than the Yellowstone event, and it’s since been involved in plenty of major eruptions, but not anything like its original explosion.
Although another super-eruption is possible – as the magma system beneath it is still definitely active – the chances are that there will be smaller eruptions taking place here in the next few hundred years or so, but nothing major.
Valles is similar, having super-erupted 1.25 million years ago, formed a caldera, and experienced some concerning activity, but it has not super-erupted since. Despite the fact that there’s clearly an active magma source beneath it, it’s likely to be a shadow of its former self, and there’s no sign of an impending super-eruption in the future.
So in terms of the US, Yellowstone’s the Big Bad – it’s the most likely to super-erupt next, while the other two may never reach VEI 7-8 ever again. But what about the rest of the world?
We can take the beautifully viridian Aira caldera out of the equation straight away. Although this vast ancient bowl did have a rather violent past - although arguably not reaching the VEI 8 level of paroxysm - all evidence points towards Mount Sakurajima, a stratovolcano nested within it, as the sole source of its output these days – and although this will one day cause trouble for the nearby, moderately-sized Kagoshima City, it will never change the world.