I went through Yellowstone many years ago and watched Ol' Faithful do it's
stuff. In those days, visitors could walk on boardwalks out among a bubbling
bunch of hot spring outlets around the famed geyser, but I understand
they've done away with much of that. It did seem a bit precarious. I kept
thinking, "What would happen if this boardwalk collapsed?"
Doc

"Uncle Wally" <sgdecember2...@yahoo.ca> wrote in message

news:1195030407.800177.206840@y27g2000pre.googlegroups.com...

http://news.independent.co.uk/world/americas/article3146417.ece#2007-...

Yellowstone: the time bomb under America

Deep beneath Yellowstone National Park lies a vast super-volcano
which, if it blew up, could devastate much of the US.
Recently, it's been a bit too restless for comfort. David Usborne
reports

Published: 10 November 2007

Visitors to Yellowstone National Park in the north-western United
States know not to be careless about the bears that roam its pines or
the many hissing and sizzling geysers that dot its magnificent
landscape. Few ever worry about being blown into space, though.

Startling new geological data published yesterday in the journal
Science suggests that it might be a good idea for most of us - and
certainly those living in the region - to be aware that there is more
to Yellowstone than grand vistas and abundant wildlife. The hot
springs are a clue to what lies beneath: seething layers of molten
magma, super-heated gases and hydrothermal liquids.

Yellowstone straddles one of Earth's most studied "hot-spots", where
fissures in the crust, created by volcanic eruptions of eons past,
have allowed giant streams of molten rock, or magma, to push closer
than normal to the planet's surface. In recent years something
intriguing - if not to say thoroughly nerve-rattling - has been going
on. The magma is on the move. And so is Yellowstone.

Over the past three years, according to the report, the ground in the
volcanic caldera that spans about 925 square miles and accounts for
much of the park's terrain has been rising towards the sky at the rate
of almost three inches per year. That is three times faster than has
ever been observed before. It raises the obvious question: what is
happening under the park? And what might be about to happen?

The study's authors are aware, of course, that the notion of
Yellowstone being some kind of humming volcanic time-bomb is not
something that tourism officials will want to advertise. And, indeed,
any kind of panic because of the new data, remarkable though it is,
would be entirely misplaced, they insist. "There is no evidence of an
imminent volcanic eruption or hydrothermal explosion. That's the
bottom line," insists Robert Smith, a professor of geophysics at the
University of Utah and the lead researcher in this study. "A lot of
calderas worldwide go up and down over decades without erupting."

It may also be reassuring to know that no very big bangs have happened
at Yellowstone for a very long time. The caldera, the walls of which
are easily discernible from some vantage points in the park, was
formed by some massive eruption past when a more classic-looking
volcanic cone was probably obliterated. And while the park is still
technically a "super-volcano" , it is estimated that it has not blown
its top for 640,000 years. If you are planning to be in the park on a
Thursday next March, therefore, the chances of it detonating that
particular afternoon are surely slim.

No one is about to take their eyes off the park, however, not least
because of these unusual new findings that suggest at least that
pressures beneath the ground are rising. Moreover, geologists are well
aware that were a major eruption indeed to happen, the impact would
rival any natural disaster the world has ever seen. Remember the
destruction when Mount St Helens flipped her lid in 1980, turning 240
square miles into a wasteland? The energy released at Yellowstone
would be many hundreds of times greater.

Moreover, Yellowstone may be due a massive release. Geologists believe
that the super-volcano beneath the park has undergone major eruptions
at roughly 650,000-year intervals. There have been about 140 such
events over 16 million years. Because the last serious explosion is
believed to have taken place 640,000 years ago - although there was a
minor flare-up 70,000 years ago - who is to say, really, that another
one is indeed not imminent? Scientists have been observing the rising
and falling of the ground at Yellowstone since 1923. The last most
rapid period of upward movement occurred between 1976 and 1985, but
only at a rate of about one inch a year. Professor Smith and his
assistants began taking their readings in 2004 with instruments aided
by satellite tracking placed at numerous spots across the caldera.
They have even observed undulations in the caldera's surface, with
some spots rising faster than others one year and then slowing down
again while different areas catch up.

In the study, Accelerated Uplift and Magmatic Intrusion of the
Yellowstone Caldera, 2004 to 2006, the authors note that while most of
the magma remains about 400 miles below the surface, a significant
plume rises to about 30 miles deep, where it spreads out horizontally
like a pancake that is larger than Los Angeles. It seems likely that
the pancake is expanding and causing the floor of the caldera suddenly
to rise.

"Our best evidence is that the crustal magma chamber is filling with
molten rock," Professor Smith explained. "But we have no idea how long
this process goes on before there either is an eruption or the inflow
of molten rock stops and the caldera deflates again." In other words,
something is afoot, but no techniques exist to forecast what comes
next. The prediction is easier for single-channel, cone volcanoes. At
a caldera such as Yellowstone, the magma could suddenly blow through
at any number of locations. "We use the term 'restless' to describe
these systems," Professor Smith said.

And what if the ground at Yellowstone does not start to go down? Well,
these calderas, he admits, "occasionally they burp". Let's hope the
park's belly-ache resolves itself - such a "burp" would shake half of
the planet.

==================

HOOROO

UNCLE WALLY

----- Hide quoted text -

- Show quoted text -