Are you worried about the end of life as we know it? Then don't just look to the sky for that catastrophic asteroid that could be heading our way. The end may come from right beneath your feet.
Super-volcanoes have probably caused more extinctions than asteroids. But until now it has been thought that these giant volcanoes took thousands of years to form -- and would remain trapped beneath the earth's crust for thousands more years -- before having much effect on the planet.
But new research indicates these catastrophic eruptions, possibly thousands of times more powerful than the 1980 eruption of Mount St. Helens, may happen only a few hundred years after the volcanoes form. In other words, they may have a very "short fuse," according to researchers at Vanderbilt University.
Such an event could make thermonuclear war or global warming seem trivial, spewing untold tons of ash into the atmosphere to block sunlight. The result would be many years of frigid temperatures, wiping out millions of species. A super-volcano that erupted 250 million years ago is now believed to have created the greatest mass extinction the world has ever seen, wiping out up to 95 percent of all plant and animal species. Some renegade scientists believe it was a volcano, not an asteroid, that killed off the dinosaurs 65 million years ago.
But is global suicide lurking right below our feet? Is a super-volcano about to blow its top? Not as far as scientists can tell. Such a volcano results from the accumulation of a giant pool of lava just a few miles below the ground, and there is no known formation anywhere on the planet that is expected to erupt in the immediate future.
Scientists, who could be wrong about that, have thought for decades that once that pool forms, it stays there for thousands of years before erupting. But the new study by geophysicists from Vanderbilt, along with colleagues at the University of Chicago and elsewhere, documents several lines of research showing that the trigger could be pulled quickly, possibly within a few hundred years.
"Our study suggests that when these exceptionally large magma pools form they are ephemeral and cannot exist very long without erupting," Vanderbilt's Guilherme Gualda said in releasing the study, published in the journal Public Library of Science ONE.
That research, as well as earlier research that led to a very different conclusion, was based on the formation of crystals in the molten magma that decay at known rates and thus provide a geological clock, dating various events in the history of the volcano.
According to Gualda, previous researchers looked at the decay of zircons, which are common in volcanic rocks, and concluded that the giant magma pools could exist for 100,000 years. But his team looked at the crystallization of quartz, the most abundant mineral in volcanic deposits, and concluded that such a pool would have to erupt in one-tenth of that time, and possibly in only about 500 years.
That makes the threat of super-volcanoes a bit more serious, but there's no reason to panic.