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FNF: YELLOWSTONE CALDERA http://www.hi.is/~joner/eaps/wh_yellv.htm
2001-04-12 JE VS: 530.4666 |
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"Source:
University Of Wisconsin-Madison (http://www.wisc.edu/)
Date:
Posted 7/23/2001
Tiny Crystals Predict A Huge Volcano In Western
United States
Tiny Crystals Predict A Huge Volcano In Western United States
MADISON - Reading the geochemical fine print found in tiny crystals of the
minerals zircon and quartz, scientists are forming a new picture of the life history
- and a geologic timetable - of a type of volcano in the western United States
capable of dramatically altering climate sometime within the next 100,000 years.
With insight gained from new analytical techniques to study crystals of zircon and
quartz, minerals that serve as veritable time capsules of geologic events, a group
of scientists from the University of Wisconsin-Madison has proposed a new
model for the origin of volcanism in young calderas.
These are volcanoes that occur over "hot spots" in the Earth and they erupt
every few hundred thousand years in catastrophic explosions, sending hundreds
to thousands of cubic kilometers of ash into the atmosphere and wreaking
climatic havoc on a global scale. "
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See the full original at:
http://www.sciencedaily.com/releases/2001/07/010723101806.htm
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"The Yellowstone Caldera
"At Yellowstone in the US, 1000 cubic kilometres of ash and pumice
spewed out 600 000 years ago, and even this was outdone when 2500 cubic
kilometres were vented two million years ago.....
If such eruptions happened today, the devastation wouldbe unthinkable.
The Yellowstone pyroclastic currents engulfed large parts of three states,
and the airborne dust covered most of the country in a grey ash blanket.
Industry, transport and agriculture would collapse overnight."
http://www.hi.is/~joner/eaps/uh_yello.htm
"
See the full original at:
http://www.hi.is/~joner/eaps/uh_yello.htm
"...Both of these shrink to insignificance when compared with Yellowstone.
- The volume of volcanic rock produced by the first Yellowstone caldera eruption
was about 600 cubic miles—
- about 17 times more than Tambora, and
- 2,400 times as much as Mount St. Helen's, an almost incomprehensible figure.
One more statistic: Ash from Tambora drifted downwind more than 800 miles; Yellowstone ash
is found in Ventura, California to the west and the Iowa to the east. It is likely the
earth has seldom in its long history experienced caldera explosions on the scale of those
that created Yellowstone.
Three gigantic caldera eruptions rocked the Greater Yellowstone Ecosystem.
The first and largest, Huckleberry Ridge caldera, blew up about 2.1 million years ago. Its center
was in western Yellowstone National Park, but it extended into Island Park, Idaho.
Welded tuff from this cycle is called the Huckleberry Ridge Tuff. The yellow rocks along
the road in Golden Gate between Mammoth Hot Springs and Swan Lake Flats are
Huckleberry Ridge Tuff. So are the tuffs that hold up much of Signal Mountain in Grand
Teton National Park, and that crop out along the west side of the Teton Range, in
Idaho.
The second great explosion formed the Island Park caldera 1.3 million years ago.
This caldera, the smallest of the three, lies just west of Yellowstone in Idaho, within
the western part of the Huckleberry Ridge caldera.
The youngest caldera, Lava Creek, erupted the Lava Creek Tuff, 0.65 million years old.
It overlaps the Huckleberry Ridge caldera, but its eastern margin is about 10 miles
farther east. Because it is the youngest, its tuffs and associated lava flows are best
exposed and its history best known. Its eruption may have destroyed the south part of
the Washburn Range."
" Earthquake data also suggest that soft or molten rock is close to the surface of
Yellowstone. Minor earthquakes jiggle Yellowstone hundreds of times each year, but
above the caldera the foci of these quakes are extremely shallow, less than three miles
below the surface. These clues suggest that the material underlying Yellowstone is still
very hot and ductile, as would be expected if a magma chamber still exists.
Gravity studies back up conclusions drawn from seismic data....
Local uplift and subsidence within Yellowstone are fast enough to be measured by
surveying techniques...Surveys in 1986 and later show this pattern of uplift has changed
to subsidence, also at a rate of about 1/2 inch a year. We do
not know if the change after 1985 represents the start of a major interval of subsidence
or a minor reversal in a longer interval of uplift, but surveys as recent as
1993 show subsidence.
These various investigations of hydrothermal features, heat flow, seis-micity,
earthquakes, gravity, and historic altitude change give us an interesting picture of what
underlies the Yellowstone Plateau. These conditions are
consistent with a large, partly
molten magma body at shallow depth that extends northeast of the caldera rim.
Although rocks underlying the rest of the caldera have low densities and low seismic
velocities, the variations are less extreme, so the rocks there may be very hot but not
necessarily contain much molten magma."
See the full original at:
http://www.yellowstonenationalpark.com/calderas.htm
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