May 1st, 2012 by Joshua S Hill
The Yellowstone “super-volcano” was in the record books for creating the fourth largest eruption known to science. “Was”, because new research has shown that the super-eruption was actually two separate eruptions, which means that the Yellowstone super-volcano is a little less super and a little more frequent.
“The Yellowstone volcano’s previous behavior is the best guide of what it will do in the future,” says Ben Ellis, co-author and post-doctoral researcher at Washington State University’s School of the Environment. “This research suggests explosive volcanism from Yellowstone is more frequent than previously thought.”
Researchers from Washington State University and the Scottish Universities Environmental Research Centre used high-precision argon isotope dating to make the new calculations, which redefined what we now know about the 2 million year old Huckleberry Ridge deposit. Instead of one big eruption 2.1 million years ago, there were actually two; the first, still “super”, produced an eruption of 2,200 cubic kilometres – approximately 12 percent less than had been previously thought – followed 6,000 years later by a second eruption of 290 cubic kilometres. The eruption would have darkened the skies with ash from southern California to the Mississippi River.
For comparison, the 1980 eruption of Mount St. Helens produced only 1 cubic kilometre of ash, while Oregon’s Mount Mazama 6,850 years ago produced 116 cubic kilometers of ash.
Co-author and post-doctoral research fellow at the SUERC Darren Mark recently helped fine tune the argon isotope dating technique. The radioactive decay rate from potassium 40 to argon 40 serves as a way for scientists to determine the age of rocks and has a precision of .2 percent. Mark recently helped improve the technique by 1.2 percent, which may sound small but is incredibly effective when working in geologic time.
“Improved precision for greater temporal resolution is not just about adding another decimal place to a number, says Mark. “It’s far more exciting. It’s like getting a sharper lens on a camera. It allows us to see the world more clearly.”
Mark’s improvements and this latest research poses a new question for scientists: are super-eruptions only detected as one large eruption because we simply don’t have the technology yet to separate closely timed eruptions?
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