When the volcano in Yellowstone National Park blew 6,400 centuries ago,
it obliterated a mountain range, felled herds of prehistoric camels
hundreds of miles away and left a smoking hole in the ground the size of
the Los Angeles Basin.
Modern Yellowstone doesn't dwell on its cataclysmic pastor its potential for another monster eruption.
Rangers tell people to keep their distance from bison and steaming geysers. But there are no signs, aside from nature's own bubbling mud pots and geysers, that visitors are wandering through the caldera of one of the largest active volcanoes in the world.
"This is a geologic park, and not many know it," said Robert Smith, a geophysicist at the University of Utah who has spent his career piecing together the story of the Yellowstone volcano. "It's not a bison park. Not an elk park. It's a geologic park."
New sensors have allowed researchers to confirm a suspicion that Smith has held for a long time: that the ancient volcano scientists dub "the beast" is a living force. The instruments record a continuing pattern of heaving and bulging and act as an early warning system.
Installed without fanfare and hidden from view, the sensitive devices are an acknowledgment that the past could be prologue, that this seemingly serene plateau could blow so hard it would make the 1980 Mount St. Helens explosion look like a sneeze.
This summer, Yellowstone was added to the nation's handful of official volcano observatories. The others, smaller but far better known, are in Hawaii, Alaska, the Cascades, and California's Long Valley.
The Yellowstone observatory consists of a string of 28 electronic detection stations scattered through the park. Related plans call for at least 100 more monitoring sites.
For Smith, who argued for years that the volcano deserved more attention than it was getting, the observatory is sweet vindication. The beast is finally getting its due.
What took so long for science to put its ear to the ground, given the fact that geophysicists have known for 30 years that Yellowstone was a major volcanic system?
For one thing, Smith said, they couldn't decide whether the Yellowstone system was still active or in its death throes. For another, it doesn't look like a volcano.
It's just too big. From a viewpoint on the north rim of the caldera, a few miles from the Yellowstone River's Upper and Lower Falls, the southern edge of the caldera is obscured. It's more than 30 miles (50 kilometers) awaywell within the massive park, but lost in the haze.