What would happen if all the world’s volcanoes went off at once? Although this is fairly unlikely to occur, it is a rather glorious thought experiment – and thought experiments are the cornerstone of the scientific process, after all.
Jessica Ball, a geophysicist and volcanologist with the United States Geological Survey (USGS), clearly relished ruminating on a volcanically-induced end-of-the-world scenario. Just recently, she spoke to Flash Forward about how she envisions a supervolcanic oblivion would come to pass, highlighting that some volcanoes would be far more dangerous than others, and in any case, the world’s climate would be changed, perhaps irreparably. It's possible, though, things would be even grimmer than this particular volcanologist is willing to suggest.
Oozes and Ash Clouds
Don't touch that. It's pretty hot. Fotos593/Shutterstock
Initially, there would be mass panic at seeing every single volcano blow its top. Volcanoes known for their slower, calmer eruptions – like Hawaii’s Kilauea or Ethiopia's Erta Ale – would just ooze liquid hot lava all over themselves, which would inconvenience anyone living nearby. However, the lava moves so slowly out of these shield volcanoes that people could run out of the way and hop on a plane.
However, the taller stratovolcanoes like Mount Fuji and fissure eruptions under ice or water, like those seen in Iceland, would cause more of a problem. Both would produce so much ash that it would blanket the sky and darken the world, plunging it initially into a freezing volcanic winter. Without sunlight, crops would fail and agriculture would collapse, along with the higher food chain.
People would starve, and anyone breathing any of that ash in would suffer slow and agonizing respiratory stoppages. Anyone hiding in buildings would be vulnerable to infrastructural collapse: Most ash is five times denser than water, and many structures aren’t designed to hold tonnes of ash falling on top of them.
In terms of the Fujis of the world, the lava and the person-squashing lava bombs would be the least of our worries. Huge, catastrophic pyroclastic flows would barrel down the slopes at supersonic speeds and would almost instantly kill anything and anyone in their path. Anyone trying to escape in a plane would find their engines melting and seizing up, as ash would find its way inside and begin to re-melt into drops of lava.