Page 18 - 2002 DT 12 issues

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The Beast Below ○ ○ Together with more data from ○ added up to only one answer: a massive
○ NASA’s remote sensing technology, ○ volcano driven by a mantle plume.
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○ Christiansen and Smith determined that ○ Over the past 17 million years, the
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eneath the grandeur of ○
Yellowstone National Park lies ○ ○ the system was a very large and very ac- ○ ○ hot-spot has caused outpourings of over
B a slumbering volcanic beast. The ○ ○ tive volcano. Smith also theorized that it ○ ○ 200 thousand square miles of basalt lava,
was fed by a magma plume from the
molten rock filling its enormous magma ○ ○ earth’s mantle, creating a “hot spot” be- ○ ○ burying parts of Washington State, Or-
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chamber is the source of Yellowstone’s ○ ○ egon, California and Nevada in lava
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spectacular phenomena. The Yellowstone ○ low the crust. The evidence suggested that ○ stacks half a mile or more thick. But fur-
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volcanic field and caldera represent the ○ starting in western Idaho, the hot-spot had ○ ther research has caused Smith to suspect
largest and most diverse collection of ○ ○ left a series of “ancient Yellowstones” as ○ ○ that other nearer-surface processes may
natural hot springs, mud pots and steam ○ ○ it bore through the southwest-moving con- ○ ○ also be fueling Yellowstone.
tinental plate over a period of at least 17
vents in the world. But like Mount St. ○ ○ million years. That movement continues ○ ○ In July of 2001, the formation of a
Yellowstone Volcano Observatory was
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Helens, Mt. Rainier and oth- ○ ○ ○ announced to strengthen the long-term
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ers, this volcano is only nap- ○ ○ ○
ping and its history is long ○ ○ ○ monitoring of the slumbering beast. A
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and violent. ○ ○ joint venture between the USGS and the
○ ○ University of Utah, it will provide a labo-
Major caldera-forming ○ ○
○ ○ ratory perched atop a living force which
eruptions 2.2 million, 1.3 ○ ○ causes the earth beneath it to rise and fall
million and 640,000 years ○ ○ ○ ○ measurably as the magma moves. Will
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ago were between 280 and ○ ○ ○ Yellowstone erupt again?
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2500 times larger in volume ○ ○ ○ A recent study of zircon and quartz
than the Mount St. Helens ○ ○ ○ ○ crystals in Yellowstone’s rocks by
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event. Even the smallest of ○
○ ○ scientists from the University of Wiscon-
these produced far more lava ○ ○
○ ○ sin–Madison, indicates that the volcanic
and ash than Mount ○ ○ cycle is waning, even as the crustal plate
Mazama, Tambora or ○ ○ ○ ○ continues to move. Still, they believe that
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Krakatoa. The combined ○ ○ ○ the volcano will produce an eruption of
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output of Yellowstone’s ○ ○ ○ “massive proportions sometime in the
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three major blows would fill ○ ○ ○ near geologic future,” perhaps within the
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the Grand Canyon. Their ash ○ ○ ○ next 100,000 years. Such an eruption
deposits have been found as ○ ○ ○ ○ would have major global consequences,
far away as Iowa, Missouri, Texas and ○ ○ today, pushing the hot-spot deeper into ○ ○ causing dramatic climate disruption and
northern Mexico. Many smaller flows ○ the continent toward Canada. ○ smothering life in the area. Whatever the
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have occurred since, gradually filling in ○ The hot spot theory was dismissed ○ eventual outcome, it is the hot spot’s geo-
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the caldera—the last of these about 70 ○ ○ when it was first published in 1973. Ev- ○ logic processes that have made the Park
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thousand years ago. However it is only ○ eryone knew that volcanos only occurred ○ the wonder that it is, creating the land-
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recently that the true significance of ○ at the margins of tectonic plates. Subduc- ○ scape and unique ecosystems that support
Yellowstone’s seismic and volcanic ac- ○ ○ tion forces pushing oceanic plates under ○ ○ Yellowstone’s diverse wildlife.
tivity has been uncovered. ○ continental crust generate the melting that ○ ○
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In 1965, the U. S. Geological Survey ○ powers volcanos. Seismic data gathered ○ ○
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(USGS) set out to define the processes ○ by the geologists between 1973 and 1998 ○ February Board and
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driving Yellowstone’s phenomena. After ○ however, showed an unusual pattern of ○ Committee Notes
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mapping the massive calderas and lava ○ earthquakes—some 15,000. Many of the ○ ○
flows, geologist Robert Christiansen ○ ○ faults were misaligned and the earthquake ○ ○ n Approved motions: up to $500
turned to geophysicist Robert Smith of the ○ swarms were uncharacteristic. They ○ to fund the second annual Kids Art Con-
University of Utah. Smith had spent most didn’t fit the conventional notions of seis- test; up to $3,000 to purchase and install
of his career studying Yellowstone micity. That, plus the geothermal activity a tamper-proof donation box for Friends,
geology. and continuing ground level fluctuations, to be located on the Scenic Drive. The
Page 2 FORRC/March, 2002