- YELLOWSTONE NATIONAL PARK -
When European settlers wandered upon this otherworld of gurgling mud pits
and angry geysers, they described it as a place where hell bubbled up.
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- They didn't guess, as geologists believe now, that three
times in the last 2 million or so years, hell blasted the earth's crust
here with a fury that can barely be imagined.
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- Most recently, some 640,000 years ago, Yellowstone's
rage toppled mountainsides, changed the course of rivers and sprayed ash
ankle deep over all of what is now the Western United States.
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- So there's understandable interest in whether it might
blow again. And when.
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- Fresh high-technology studies of the underground cauldron
-- and discovery of a bulge on the floor of Yellowstone Lake -- show anew
the region as geology-in-the-making.
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- There's evidence that the bulge - described by one scientist
as an "inflated plain" - might be throbbing from the pressure
that pushed it up in the first place.
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- That detection has scientists captivated, not frightened,
even as it fills amateur geologists with dread.
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- Those laymen worry that the pressure cooker of Yellowstone
is set to burst.
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- Even smaller blasts - say the size of Mount St. Helens
- that come about every 20,000 years or so can rearrange Yellowstone's
scenery. The most recent of those was 70,000 years ago.
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- Some urge government engineers to gradually vent steam
and magma by drilling, rather than wait for a seemingly imminent, giant
and calamitous blast.
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- "If nothing is done there will be an unimaginable
disaster," went discussion at one Internet discussion site. But nobody
even seems to be thinking about it."
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- But the geologists who explore the caldera -- the collapsed
supervolcano that is Yellowstone -- share neither such alarmist doom nor
faith in methods for taming the forces boiling underground.
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- For starters, drilling here would spoil the natural setting
of the world's first national park in 1872, said park geologist Hank Heasler.
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- What's more, he said, it would do no good. The magma
chamber miles below the park is mostly like a hardened sponge and is essentially
self-sealing.
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- "Besides, it's too big," he said, noting the
caldera measures 35 miles by 45 miles. "We're on the skin of the apple.
We can leave little bruises, but we can't affect the flavor of the fruit."
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- Discovery of the bulge
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- Government and university scientists dismiss new-born
worries about Yellowstone, about the bulge beneath the lake, and about
recent changes at the park's Norris geyser basin. Mostly, they marvel at
their out-sized laboratory.
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- They point out that, literally, the landscape of Yellowstone
is always shifting. Last year, typical for the era when such measurements
have been made, there were about 2,300 earthquakes in the park.
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- "Geologists usually look at something that formed
millions of years ago and is now dead," said Lisa Morgan, a U.S. Geological
Survey geologist. "But in Yellowstone, it's something that's happening
right now."
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- The bulge, discovered with newly employed high-tech gadgetry
and techniques led by Morgan last year, might be relatively new. Or, she
said, it could have formed millennia ago.
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- "I don't know whether this thing is active now in
terms of inflation or not," Morgan said.
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- So what set off the panic in the it's-time-to-drill crowd?
A few combinations of coincidence and research.
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- First, state-of-the-art mapping revealed some features
of Yellowstone that were previously unknown. Next were more obvious changes
to the Norris geyser basin were taking place. Combined with what scientists
see as sensational press coverage, these triggered alarm in some circles.
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- Beginning in 2002, Morgan led a team that produced the
first detailed topographical maps of the bottom of Lake Yellowstone --
a pristine basin fed by 144 mountain streams and drained by the Yellowstone
River.
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- Morgan deployed robotic submarines. She bounced sonar
waves off the lake bed and at frequencies that penetrated deeper into that
bottom. She ordered magnetic measurements of the rock. The result was a
map whose precision befit the digital age.
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- "It's like having the cataracts taken off of your
eyes," she said.
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- The scientific view was delightful. Through roughly the
middle of the lake ran the edge of the Yellowstone caldera, that sunken
supervolcano crater, a tad straighter and more to the east than previously
thought.
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- In a northwestern corner of the lake was a spire field,
column after column of towers ranging from just more than 3 feet to a little
less than about 30 feet wide and sometimes more than two stories high.
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- Morgan said they were formed around hydrothermal vents,
where sulfur-laced, super-heated water jets into the lake. The sulfur attracts
bacteria. The bacteria become filled with silica and build layer upon layer
-- stalagmite-style -- over the eons.
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- Perhaps most dramatic was the discovery of the bulge,
what Morgan labeled an "inflated plain," to suggest it is evidence
of pressure from below the lake nudging at the earth's skin.
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- Roughly the size of a few city blocks, she said it was
pocked with hydrothermal vents that demonstrate it is close to the magma
chamber below and possibly under more pressure that other places in the
caldera.
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- If it were to blow, it would not be the first the lake
has seen. An explosion at the northeast edge about 13,000 years ago left
a three-mile-wide crater at Mary Bay. The larger West Thumb of the lake
was the result of another blast.
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- Like Harry Potter
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- While scientists were scanning the lake with sonar equipment
in September 2003, one long-time Yellowstone researcher noticed an especially
strong sulfur scent rising from bubbles in the water. He'd spent years
on the lake but never noticed the smell to be so strong.
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- But the observation came at a time when it was unusual
to be on the lake. Researchers typically leave by summer's end. In the
fall, the lake is nearing its lowest levels, when there's less mountain
runoff to dilute the sulfur-tainted water from underground hydrothermal
venting.
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- "Maybe it's been that way during that season every
year for a long time," Morgan said. "We don't know."
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- Meantime, there was a shift this year in the baffling
water table at the Norris geyser basin about 20 miles away -- leaving some
former bubbling areas dry and creating neon green pools elsewhere that
can scald to death wayward bison.
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- With at least one long-dormant geyser spitting to life
near a trail, the park was forced to shut off a large portion of the boardwalk
that winds through the steamy plateaus.
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- "Safety first," said Heasler, the park geologist.
"The problem is, we don't know what's causing this."
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- To children, he compares the enigma of Yellowstone geology
to the seven volumes that are expected in the Harry Potter series.
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- "It's as if we're just into the first paragraph,"
he said. "There's an awful lot we don't know yet."
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- He emphasizes that discoveries such as the spires and
the bulge are newly noticed, not necessarily new. So Heasler said they
couldn't be taken as evidence that there had been any radical developments
at Yellowstone in recent years.
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- The shift at the Norris geysers, he said, is the same
sort of change that has made the place remarkable since scientists started
paying attention. It would be more unusual if things stopped changing.
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- Still, Heasler said he received several anxious e-mails
a week from people worried about an eruption at Yellowstone that could
kill millions.
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- Bob Smith, a geophysics professor at the University of
Utah, has been studying what he calls the living caldera" of Yellowstone
for decades. He noted that there have been no unusual seismic activities
at the park this year that might precede bigger trouble.
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- "These things don't go like clockwork," said
Smith, author of Windows into the Earth: The Geologic Story of Yellowstone
and Grand Teton National Parks. "The hazard ... is almost too small
to calculate."
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- Copyright 2003, azcentral.com. All rights reserved.
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- http://www.azcentral.com/news/articles/1007Yellowstone-ON.html
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