Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now公仔箱論壇7 \6 ~/ ^9 T% t) \4 F. g) S3 z/ o
- Most deadly event that can hit Earth short of asteroid
- Scientists believed they took 100,000 years to build up
- Instead, figure could be just hundreds
- Supervolcano believed to be simmering under Yellowstone in U.S.
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A 'supervolcano' eruption is the most catastrophic natural disaster that can hit our planet, short of an asteroid impact - and now scientists believe they may build up a deadly head of steam far faster than we thought.
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Instead of the process taking hundreds of thousands of years, it could take just hundreds.tvb now,tvbnow,bttvb4 A3 M9 ^# q* z; V
% p* c7 d" Z' t$ _4 N公仔箱論壇The news could be bad for the US, where a supervolcano is said to be simmering beneath Yellowstone National Park. If it erupted, two thirds of the country could be rendered uninhabitable.
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Eruption: Supervolcanoes with the power to destroy human civilisations may build up a deadly head of steam far faster than scientists believed
2 d0 [* \- {8 s7 m) uSupervolcanoes are fuelled by giant pools of magma that form deep underground.
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6 H" ~0 f( B: g/ Q( }Geologists had thought it took between 100,000 to 200,000 years for a supervolcano magma pool to build up enough pressure to erupt.
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But the new study suggests that the giant magma bodies may only exist for a few thousand years, or even a few hundred, before exploding.
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A magma reservoir six miles below Yellowstone has been rising at a record rate since 2004.
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The Wyoming park sits above a gigantic plume of hot and molten rock that begins at least 400 miles beneath Earth's surface and rises to 30 miles underground, where it widens to about 300 miles across.
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2 `$ ]& Z$ L& k7 N( OBlobs of magma occasionally break off from the top of the plume, and rise farther, resupplying the magma chamber beneath the Yellowstone Caldera.
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; g* P# R/ V2 `' N0 p _Steaming Mud Volcano at Yellowstone National Park in winter. Researchers now believe that the supervolcano beneath the park could be more active than thought 公仔箱論壇1 W0 w" ^3 Q2 V1 H" p, u4 A7 m0 b
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The news could be bad for the US, where a supervolcano is said to be simmering beneath Yellowstone National Park. If it erupted, two thirds of the country could be rendered uninhabitableTVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。% u: X; y' e5 e, V+ f- V! S
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Castle Geyser and sunrise Yellowstone National Park Wyoming: Researchers now believe that the huge 'supervolcano' beneath the park is far more active than previously thought
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Resembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.2 ?) q4 Q, U+ o2 Z& j" M9 p8 D
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( m# {( _5 I5 [4 u4 b' OTVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。The supervolcano has erupted a total of three times in the last 2.1 million years. Scientists believe it could be due to erupt again.5.39.217.76! m {2 N% F9 z: r0 b7 n
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! O ` J- ], j' uTVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。A full scale eruption at Yellowstone would be 1,000 times more powerful than the volcanic blast that tore apart Mount St Helens in 1980.tvb now,tvbnow,bttvb8 @! X; c. I6 r Q* |0 X
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There is evidence that a similar super-eruption in Indonesia 74,000 years ago came close to wiping out the entire human species.
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The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.9 P! L+ |/ ~, R$ i% S" H
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Several independent lines of evidence indicated that the magma pool erupted within a few thousand years, perhaps within a few hundred years, covering half the North American continent with smouldering ash.
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# R' H. W- ^/ X- A8 @: X5.39.217.76The scientists based their estimate on quartz crystallisation rates. Previous studies have relied on the growth of zircon crystals, which is said to be a less accurate method.
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The research is published in the online journal Public Library of Science ONE.5.39.217.76* A5 Y! m; W& G; Y6 p) d
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Lead scientist Dr Guilherme Gualda, from Vanderbilt University in Nashville, Tennessee, said: ‘Our study suggests that when these exceptionally large magma pools form they are ephemeral and cannot exist very long without erupting.5.39.217.76) D- P1 ~9 I; Z% u# v# J
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3 n' P5 U: l4 E) \5 \$ r公仔箱論壇‘The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem.’tvb now,tvbnow,bttvb7 U i6 d" U! h
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He said regions such as Yellowstone should be monitored regularly to provide advance warning of a catastrophic super-eruption. |
發表於 2012-6-1 01:50 AM
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發表於 2012-6-1 08:11 PM
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