Yellowstone's Explosive Secret

For years, CBS News Correspondent Sandra Hughes reports, scientists have tried to understand the dynamic nature of Yellowstone National Park.

"It's beautiful up here, everybody should see this at one time or another," says one appreciative observer.

Scientisth Lisa Morgan may have unlocked one piece in the puzzle, deep below the park's biggest lake.

"It is kind of the last unmapped frontier in Yellowstone National Park," says Morgan.

What she found looks more like the surface of the moon. Using sonar she's identified a massive bulging dome the size of seven football fields. The only other underwater dome in Yellowstone was the site of a major explosion.

"The most extreme event, which occurred 13,800 years ago, went about as far as five miles away from source," says Morgan.

It spewed boiling water, steam and rocks, and the fear of it happening again started another explosion of sorts: this one on the Internet. Online doomsday scenarios are swirling all over chat rooms telling visitors to stay away. Yellowstone, they warn, could blow.

Yellowstone National Park sits on top of one of the most active volcanoes in the world with more than 10,000 vents, geysers and bubbling hot springs. That's part of the reason more than 3 million people come here each year.

So for Morgan it is important to clarify. She doesn't think the big dome is ready to explode, but park ranger Hank Heasler says Yellowstone is unpredictable.

"The bottom line is we still don't know all that much about what's going on at Yellowstone," says Heasler.

So he takes the job of keeping visitors safe seriously, constantly monitoring temperatures.

And that's not always easy. A trail near the Norris Geyser was closed last summer and is still boiling hot enough to burn through shoes.

"If the temperatures here gets above boiling, then we know that there's a potential for the water to just rapidly flash to steam and cause one of these hydrothermal explosions," says Heasler.

Which is exactly what Old Faithful and her companion geysers do almost daily and that's why scientists from around the world are watching this latest discovery and wondering what nature has planned next.