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The eruption of a super
volcano "sooner or later" will chill the planet and threaten human
civilization, British scientists warned Tuesday.
And now the bad news:
There's not much anyone can do about it.
Several volcanoes around
the world are capable of gigantic eruptions unlike anything witnessed in
recorded history, based on geologic evidence of past events, the scientists
said. Such eruptions would dwarf those of Mount St. Helens, Krakatoa, Pinatubo and anything
else going back dozens of millennia.
"Super-eruptions are
up to hundreds of times larger than these," said Stephen Self of the United Kingdom’s (U.K.) Open University.
"An area the size of
North
America
can be devastated, and pronounced deterioration of global climate would be
expected for a few years following the eruption," Self said. "They
could result in the devastation of world agriculture, severe disruption of
food supplies, and mass starvation. These effects could be sufficiently
severe to threaten the fabric of civilization."
Self and his colleagues
at the Geological Society of London presented their report to the U.K.
Government's Natural Hazard Working Group.
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What's in Store
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The predicted effect a
super volcano at Yellowstone. Click to enlarge.
Super Evidence
In the Jemez Mountains, near Santa Fe, New Mexico, sits the Valles
Caldera -- the circular feature at left in this false-color satellite
image (vegetation is red). It's about 15 miles (24 kilometers) wide,
made by two super-eruptions 1.6 and 1.1 million years ago.
The rocky mound
below, the result of the older eruption, is 820 feet (250 meters)
thick.
Satellite image:
Landsat
Middle photo: S. Self
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"Although very rare
these events are inevitable, and at some point in the future humans will be
faced with dealing with and surviving a super eruption," Stephen Sparks
of the University of Bristol told LiveScience in
advance of Tuesday's announcement.
Supporting evidence
The warning is not new.
Geologists in the United States detailed a similar scenario in
2001, when they found evidence suggesting volcanic activity in Yellowstone National Park will eventually lead to a
colossal eruption. Half the United States will be covered in ash up to 3
feet (1 meter) deep, according to a study published in the journal Earth
and Planetary Science Letters.
Explosions of this
magnitude "happen about every 600,000 years at Yellowstone," says Chuck Wicks of the
U.S. Geological Survey, who has studied the possibilities in separate work.
"And it's been about 620,000 years since the last super explosive
eruption there."
Past volcanic
catastrophes at Yellowstone and elsewhere remain evident as giant collapsed basins
called calderas.
A super eruption is a
scaled up version of a typical volcanic outburst, Sparks explained. Each is caused by a
rising and growing chamber of hot molten rock known as magma.
"In super eruptions
the magma chamber is huge," Sparks said. The eruption is rapid,
occurring in a matter of days. "When the magma erupts the overlying
rocks collapse into the chamber, which has reduced its pressure due to the
eruption. The collapse forms the huge crater."
The eruption pumps dust
and chemicals into the atmosphere for years, screening the Sun and cooling
the planet. Earth is plunged into a perpetual winter, some models predict,
causing plant and animal species disappear forever.
"The whole of a
continent might be covered by ash, which might take many years -- possibly
decades -- to erode away and for vegetation to recover," Sparks said.
Yellowstone may be winding down geologically,
experts say. But they believe it harbors at least one final punch. Globally,
there are still plenty of possibilities for super volcano eruptions, even as
Earth quiets down over the long haul of its 4.5-billion-year existence.
"The Earth is of
course losing energy, but at a very slow rate, and the effects are only
really noticeable over billions rather than millions of years," Sparks said.
Human impact
The odds of a globally
destructive volcano explosion in any given century are extremely low, and no
scientist can say when the next one will occur. But the chances are five to
10 times greater than a globally destructive asteroid impact, according to
the new British report.
The next super eruption,
whenever it occurs, might not be the first one humans have dealt with.
About 74,000 years ago,
in what is now Sumatra, a volcano called Toba blew with a force estimated at 10,000 times
that of Mount
St. Helens.
Ash darkened the sky all around the planet. Temperatures plummeted by up to
21 degrees at higher latitudes, according to research by Michael Rampino, a
biologist and geologist at New York University.
Rampino has estimated
three-quarters of the plant species in the Northern Hemisphere perished.
Stanley Ambrose, an
anthropologist at the University of Illinois, suggested in 1998 that Rampino's
work might explain a curious bottleneck in human
evolution: The blueprints of life for all humans -- DNA -- are remarkably
similar given that our species branched
off from the rest of the primate family tree a few million years ago.
Ambrose has said early
humans were perhaps pushed to the edge of extinction after the Toba eruption
-- around the same time folks got
serious about art and tool making. Perhaps only a few thousand survived.
Humans today would all be descended from these few, and in terms of the
genetic code, not a whole lot would change in 74,000 years.
Sitting ducks
Based on the latest
evidence, eruptions the size of the giant Yellowstone and Toba events occur at least
every 100,000 years, Sparks said, "and it could be as
high as every 50,000 years. There are smaller but nevertheless huge eruptions
which would have continental to global consequences every 5,000 years or
so."
Unlike other threats to
mankind -- asteroids, nuclear attacks and global warming to name a few --
there's little to be done about a super volcano.
"While it may in
future be possible to deflect asteroids or somehow avoid their impact, even
science fiction cannot produce a credible mechanism for averting a super
eruption," the new report states. "No strategies can be envisaged
for reducing the power of major volcanic eruptions."
The Geological Society of
London has issued similar warnings going back to 2000. The scientists this
week called for more funding to investigate further the history of super
eruptions and their likely effects on the planet and on modern society.
"Sooner or later a
super eruption will happen on Earth and this issue also demands serious
attention," the report concludes.
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USGS Open-File Report 2005-1164
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An Assessment
of Volcanic Threat and Monitoring Capabilities in the United States:
Framework for a National Volcano Early Warning System
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Mount
St. Helens,
Washington, reawakens on October
1, 2004.
USGS photo.
DOWNLOAD
the report [2.8-MB PDF file]
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A National Volcano
Early Warning System – NVEWS – is being formulated by the Consortium of
U.S. Volcano Observatories (CUSVO) to establish a proactive, fully
integrated, national-scale monitoring effort that ensures the most
threatening volcanoes in the United States are properly monitored in advance
of the onset of unrest and at levels commensurate with the threats posed.
Volcanic threat is the combination of hazards (the destructive natural
phenomena produced by a volcano) and exposure (people and property at risk
from the hazards).
The United States has abundant volcanoes, and over
the past 25 years the Nation has experienced a diverse range of the
destructive phenomena that volcanoes can produce. Hazardous volcanic
activity will continue to occur, and – because of increasing population,
increasing development, and expanding national and international air
traffic over volcanic regions – the exposure of human life and enterprise
to volcano hazards is increasing. Fortunately, volcanoes exhibit precursory
unrest that if detected and analyzed in time allows eruptions to be
anticipated and communities at risk to be forewarned with reliable
information in sufficient time to implement response plans and mitigation
measures.
In the 25 years since
the cataclysmic eruption of Mount St. Helens, scientific and technological
advances in volcanology have been used to develop and test models of
volcanic behavior and to make reliable forecasts of expected activity a
reality. Until now, these technologies and methods have been applied on an
ad hoc basis to volcanoes showing signs of activity. However, waiting to
deploy a robust, modern monitoring effort until a hazardous volcano awakens
and an unrest crisis begins is socially and scientifically unsatisfactory
because it forces scientists, civil authorities, citizens, and businesses
into “playing catch up” with the volcano, trying to get instruments and
civil-defense measures in place before the unrest escalates and the
situation worsens. Inevitably, this manner of response results in our
missing crucial early stages of the volcanic unrest and hampers our ability
to accurately forecast events. Restless volcanoes do not always progress to
eruption; nevertheless, monitoring is necessary in such cases to minimize
either over-reacting, which costs money, or under-reacting, which may cost
lives.
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