|« A geyser erupts in Yellowstone National Park in Wyoming, U.S.|
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It’s the stuff of movies. Massive volcanic eruption, ash clouds turning the sun and moon black or red. Weather patterns altered. Artificial winter.
It is also the stuff of historical record. Three times in observable geologic history, Yellowstone’s massive volcano has erupted. The latest was a little over half a million years ago, say scientists. When it blew, millions of tons of rock were evaporated, turned to ash and projected 25 miles into the atmosphere. Massive earthquakes ripped apart geological formations. The sun was blocked out. Regional temperatures dropped, and ice and snow froze large chunks of the continent.
Today, the results of that eruption can be seen in the Yellowstone caldera—a massive depression, 34 miles by 45 miles in size.
Why is this important? On January 19, National Geographic reported that Yellowstone may be becoming active again. Beginning in 2004, scientists began noticing a disturbing phenomenon. The ground above the caldera was beginning to rise—as much as 2.8 inches a year. By 2010, the rates had slowed, but the ground continues to swell.
“It’s an extraordinary uplift, because it covers such a large area and the rates are so high,” said the University of Utah’s Bob Smith, a longtime expert in Yellowstone’s volcanism.
Other evidence of increasing volcanic activity comes in the form of earthquakes. Between Dec. 26, 2008, and Jan. 8, 2009, some 900 earthquakes rattled Yellowstone Lake—almost eight times as many as the long-term average.
Yet a volcanic eruption is not something we need to worry about yet, say scientists. For example, back in 1976 the ground above Yellowstone began to rapidly rise, leading some people to conclude that an eruption might be imminent. However, in 1985 the expansion mysteriously stopped, and the ground began to deflate.
Scientists also think the swelling magma reservoir is four to six miles below the surface at this point. Had it been closer, “we’d have been a lot more concerned,” said Smith.
But even if scientists were sure that a Yellowstone eruption was imminent, there is nothing they could do to prevent it. It is a stark reminder that despite awesome advances in science and technology, mankind is still incredibly vulnerable to the whims of nature.