Planning a summer vacation? How about visiting one of the biggest, meanest active volcanoes on earth? It's right in our own backyard, just a five-hour drive north, at Yellowstone.


People come to the nation's first park every year to see bear, elk and herds of bison, but most visitors never realize they're inside the mouth of a volcanic beast.

The mouth of the Yellowstone super volcano is big. The caldera -- the crater left by an eruption -- is roughly 14-hundred square miles. The southern half of the national park is swallowed by the caldera.

Super eruptions are the biggest blasts on earth. Good thing they are rare. A super eruption hasn't occurred in the recorded history of man.

So how do we know they will be big? A professor emeritus of geophysics at the University of Utah and leading expert on the Yellowstone super volcano, Robert Smith has found enough clues to piece together a picture. "We have in the rocks captured the geology of Yellowstone. We can see the results of these three giant eruptions which occurred at 2-million, 1.2 million and 640,000 years ago."

He said the first super eruption at Yellowstone was 2,500 times bigger than the 1980 eruption of Mount St. Helens. Ash from that eruption fell over much of the American West and Midwest reaching all the way to the Gulf of Mexico. Herds died on the plains. And the ash that remained in the upper atmosphere circled the globe plunging it into a volcanic winter that probably lasted years.

Here's the short version of what would happen If such an eruption happened today: The explosion and pyroclastic flow (think a tsunami of superheated gas, rock and ash) would level the park and surrounding communities. A few inches of ash would fall on Salt Lake. Add a little rainfall with that ash and some roofs would collapse. No harvest would be possible in America's bread basket. And of course, there would be that volcanic winter lasting years.

Scientists are not only giving us a clearer picture of a super eruption, but also what fuels it. Using a new technique that makes images with electrical and magnetic fields in the earth, scientists at the University of Utah have been looking deep into the earth. Michael Zhdanov, professor of geophysics said, "Now we can see the unseeable (sic). Now we can see through non-transparent media like rocks."

The result: the magma plume below Yellowstone is even bigger than first thought. The plume looks like a tilted tornado that extends out under Idaho, Montana and Wyoming. It is made up of hot and partly molten rock surging up into the earth's crust from the mantle.

In spots under the park, domes of magma from the plume are just a thin 5-miles below ground. Magma that close to the surface lifts the land, triggers earthquakes and heats ground water.

"Why are all the hydrothermal features here?" Heasler continued, "The geysers? The mud pots? The steam vents? The hot springs? It's because of the heat beneath our feet." There are more hydrothermal features in Yellowstone than any other place on earth.

In other words, you can thank the volcano for Old Faithful.

Internet prophets of doom are quick to predict a super eruption. Their predictions are often based on exaggerations of all the new scientific data available in real time on the web from the Yellowstone Volcano Observatory.

But scientists who know Yellowstone best now believe a super eruption won't happen for another 100-thousand years ... give or take a few thousand.