Yellowstone Passing Gas at One Blimp per Week

Talk about passing gas: Vast stores of helium are escaping from the steam vents and hot springs of Yellowstone National Park after being trapped within Earth's crust for up to 2 billion years, according to new research.

In a study published Wednesday in the journal Nature, researchers with the U.S. Geological Survey determined that the famed national park was releasing hundreds -- if not thousands -- of times more helium than anticipated.

In fact, researchers say, the escaping helium -- about 60 tons per year --  is enough to fill one Goodyear blimp every week.

They also calculate that this "sudden" release of gas began roughly 2 million years ago, with the advent of volcanic activity there.

"That might seem like a really, really long time to people, but in the geologic time scale, the volcanism is a recent phenomenon," said study coauthor Bill Evans, a research chemist at the USGS office in Menlo Park, Calif.

Helium, or more accurately the isotope helium-4, is produced in Earth's crust as uranium and thorium decay. Often, this nonradioactive, crustal helium is swept away by groundwater, or freed as a result of tectonic movement.

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