Could a single volcanic eruption destroy all life on Earth?

Just because you don't live near an active volcano doesn't mean you're immune to a catastrophic volcanic eruption.

Ever heard of a supervolcano? It's -- surprise! -- a really big volcano. (But it doesn't always look quite like what you'd think. Some of them, the calderas, look more like craters than cones.) Mount St. Helens or Iceland's Eyjafjallajökull are laughably small (very hot) potatoes compared to the realities of a lava under a gigantic caldera.

The question about supervolcanoes, it turns out, isn't whether one could destroy all life on Earth. It's when will it do it again.

That's right, folks. Around 200 million years ago, a supervolcano erupted with such insistent energy that 75 percent of the species on the planet were eradicated. It was so gigantic that it pulled apart North America and Africa and created the Atlantic Ocean in between. For 600,000 years, the supervolcano called CAMP (Central Atlantic Magmatic Province) erupted over and over [source: Newitz].

Now here's the thing that's bad news to all of those who are smugly enjoying their volcano-free neighborhoods. It wasn't that lava covered everything in sight or even that volcanic ash rained down hard enough to choke everything. Instead, it was the fallout of the pollution of the event; CO2 and carbon levels, for instance, exploded. The environment was ruined. Very little was able to bounce back. (Interesting to note that after the apocalypse, it was dinosaurs who were eventually able to evolve and take over before their own catastrophic end, proving that nobody wins for long [source: Blackburn, et al.].)

So are we vulnerable to another destructive eruption? In short, yes. Below Yellowstone Park lies a caldera that would knock not just your personal socks off, but the socks of those worldwide. Scientists recently discovered that the caldera is 55 by 20 miles (89 by 32 kilometers), and 3 to 9 miles (5 to 14 kilometers) below the surface [source: News.Au].

To put it in perspective, a Yellowstone eruption would be 25,000 times bigger than Mount St. Helens [source: Sealy]. And once again, it wouldn't necessarily be the lava flows and ash that kill you; it might be the terrible fallout from the lava flows and ash that destroy the Midwest, or the global cooling that would happen as a result.