‘Beast’ Is Alive in Wyoming

When the volcano here blew, 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 past or 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, telling visitors that they 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 still 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 Mt. St. Helens explosion look like a sneeze.

This summer, Yellowstone was finally 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.

So why did it take 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 away--well within the massive park, but lost in the haze.

The last huge eruption was more than 600,000 years ago. Since then, a series of smaller ones have filled in the caldera “like tubes of toothpaste squeezing out all over the place,” Smith said. The 3,000-foot-thick glaciers of the last Ice Age erased edges of the caldera, which is now a broad, undulating plateau rimmed by mountains.

Most volcanoes bloom at the warring edges of the Earth’s massive tectonic plates, not in the middle of a continent.

But once you know where and how to look, the volcano becomes obvious, Smith said. There are bulges where magma surges upward and swarms of earthquakes as the magma resettles. Traces of former volcanoes are splayed out across the land.

For 45 years, Smith has hiked, skied and boated through the park’s remote regions. At 62, he still jumps at the chance to ride a horse for a week into the back country, though with today’s technology he doesn’t have to. The seismometers and Global Positioning System units that measure the land’s smallest shakes and deformations beam data to Smith’s seventh-floor lab in Salt Lake City and to the pager clipped onto his belt.

He is also making use of the newest technologies--satellites that measure the Earth’s subtlest twitches and seismic tomography that takes advantage of earthquake waves to probe the Earth’s internal workings.

A native of Logan, Utah, Smith spent his summers at Wyoming’s Jackson Hole. On Aug. 19, 1959, he was taking a college geology field course in southern Idaho when the ground started to rumble. It was one of the 15 largest earthquakes the Lower 48 has seen--the magnitude 7.5 Hebgen Lake earthquake, centered just west of Yellowstone, 250 miles from him.

Eighty million tons of rock tumbled into the Madison River, damming it to create a large lake. Rock fell on sleeping campers, killing 28 people. The massive stone fireplace in the lobby of the Old Faithful Inn 25 miles away was reduced to rubble.

A few days later, Smith was at the scene, observing a mountain that had crumbled and roads that had slid off course.

Despite his limited scientific training, he suspected that something larger was going on, that other unseen forces were at play. He thought there might be far more to this earthquake than surface rocks revealed.

“That’s what really hooked me,” he said.

Smith came back to the park 10 years later, armed with a doctorate in geophysics. He had turned down jobs in California, the epicenter of earthquake studies, because he believed that there were important discoveries to be made a thousand miles away from the San Andreas fault.

It was no secret that the earth shook periodically around Yellowstone. But without the proper monitoring equipment in place, no one knew how often it happened or why. Smith set up seismometers and found earthquakes by the hundreds.

“It was virgin territory. Every time we set up a new seismic station, we’d get a new story,” he said.

The Basin and Range country that extends from California to Montana is one of the most seismically active regions east of the San Andreas. It is being stretched apart as tectonic plates beneath it move.

But the earthquakes Smith started tracking there three decades ago--15,000 between 1973 and 1998, often in swarms--didn’t altogether fit conventional notions of seismicity. There were quakes where you would expect them to occur, along north/south fault lines perpendicular to the stretching. But there were also some along parallel fault lines--activity that seemed to have no relation to the stretching.

Smith started thinking about the quakes in combination with Yellowstone’s famously unstable plumbing. Was it possible that both the quakes and the geysers were products of volcanic action, of underground magma flows?

Steaming Ground, Bubbling Water

It is obvious at first glance that Yellowstone is a volatile landscape. The ground, the hottest in North America, steams. Pools of sapphire and opaline water bubble. Thick, white minerals encrust the land. Sulfur wafts through the air. And of course, geysers like Old Faithful erupt.

The Native Americans who first saw this land weren’t so far off when they described the geysers as the “result of combat between the infernal spirits.” A beaver trapper in 1830 compared the park’s steaming springs to the budding industrial landscape of Pittsburgh. Another called it “the place were hell bubbled up.”

In 1922, geologist T.A. Jaggar made a startlingly precise assessment after traveling the park on horseback.

“The mountains are falling all the time,” he said. “Something underneath is shoving them up.”

The description explains what happens to mountains atop a volcano: The swelling magma pushes them upward; the subsequent explosion then destroys them and engulfs their remains.

The view was updated in 1958 when Joe Boyd, a graduate student from Harvard, examined the park, confirming that it was a large volcano.

In 1965, a team led by Robert Christiansen of the U.S. Geological Survey mapped the massive caldera and various lava flows in detail while NASA tried out a new remote-sensing technology in the region.

“It was not a surprise it was a young volcano,” Christiansen recalled. “It was a surprise it was as young as it is.”

He turned to Smith, whose seismic data would reveal whether the volcano was still rumbling. Together, the two men were able to see the system for what it was: a very active and large volcano that had sculpted much of the Northwest.

Smith and Christiansen saw evidence that a huge plume of magma rose from deep within the Earth and bored through the continental plate. As the plate moved southwest, the “hot spot” left a series of what Smith terms “ancient Yellowstones” across a 500-mile swath of southern Idaho from Oregon to Montana.

The hot spot theory was widely dismissed when it was introduced by Smith in 1973. Accepted wisdom said volcanoes were found at the edges of tectonic plates and that hot spots occur mainly on the sea floor.

“It took people a while to catch on,” Smith said.

The evidence, ultimately, was incontrovertible.

There was the blasted topography, the layers of lava flows, the misaligned earthquake faults and Yellowstone’s superheated, effervescent plumbing. Only one force was big enough to account for it all: a massive volcano. What Smith still didn’t know was whether it was asleep.

In the mid-1970s, while surveying an old benchmark put into place when the first roads were cut through Yellowstone in 1923, Smith found that the ground had risen three feet in five decades.

There could be only one explanation: The volcano was bulging upward. Smith and his students spent two years confirming the observation. By 1979, when he published the findings in the journal Science, even skeptics were becoming convinced that Yellowstone was an active volcano.

Redefining Hot Spots

The caldera rose an inch a year until 1985. Then a swarm of earthquakes occurred nearby. By 1987, measurements showed that the caldera was falling an inch a year. In 1995, it started rising again. The caldera is now bulging again, toward the southwest.

“It’s a huffing, puffing, breathing volcano,” said Smith, who has detailed his decades of studying the volcano in a book with Lee Siegel titled “Windows Into the Earth.”

Confirmation that the volcano was active was one of the most important factors in getting the new observatory established. The movement of the volcano also suggests a controversial new idea that is forcing many geologists to rethink the very definition of hot spots and how they work.

Until Smith came along, most scientists believed that hot spots originate 1,800 miles down, at the boundary between the Earth’s core and mantle. The newly revealed geology of Yellowstone suggests that this hot spot may be very shallow, born of the vagaries of heat and changing pressures or some other process yet unknown.

As far as it goes, the scientists’ work has yet to answer the most important question of all: Will the volcano blow its top again?

New studies by a research team at the University of Wisconsin that analyzed tiny crystals within hardened lava suggest a “dying, but still potent, cycle of volcanism.”

Some believe that the hot spot is moving under the Rocky Mountains, a much thicker and colder part of the continent, and that it will be effectively capped. Others argue that the cap won’t stop the fury of the hot spot.

Smith and Christiansen can’t say for sure, but they know the volcano is not dead. There is no reason, they say, it won’t blow again.

Christiansen doubts the likelihood of another cataclysmic eruption any time soon, but he doesn’t rule out something smaller. Earthquakes, rockslides and steam explosions from geyser basins are all possible. A blowout on the scale of Mt. St. Helens is conceivable, he said, adding: “We need to be prepared.”

The National Park Service scientist in charge of worrying about visitor safety is Paul Doss, who served this year as the park’s geologist and is a professor at Southern Indiana University. He is aware of the risks.

“We are, by definition, funneling visitors into the area where we know the hazards are,” Doss said. But the park doesn’t want to keep visitors away from the natural features and processes that make Yellowstone what it is. “That’s the primary attraction of the park,” he said.

A side benefit of the observatory, Doss said, is that it might help visitors realize they are driving, hiking, eating and sleeping inside a massive volcano.

“It’s here,” he said. “And it’s bigger than you can even imagine.”

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Yellowstone’s Volcanic Activity

A volcanic eruption more than 600,000 years ago wiped out a mountain range that ran through what is now Yellowstone National Park and left a 30-mile-wide, crater-like basin.

Source: “Windows Into the Earth,” by Robert Smith and Lee Siegel