Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right nowTVBNOW 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。2 E' W% q; F+ F
- 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.
# b3 D( ?) a* u' `TVBNOW 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 '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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0 e2 M+ u; H6 A ^5.39.217.76Instead of the process taking hundreds of thousands of years, it could take just hundreds.
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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 uninhabitable.+ a1 F j* D6 ?" A
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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 believedtvb now,tvbnow,bttvb8 `$ H8 x' P. {* |" \
Supervolcanoes are fuelled by giant pools of magma that form deep underground.
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Geologists had thought it took between 100,000 to 200,000 years for a supervolcano magma pool to build up enough pressure to erupt.3 {0 o, [/ j! X' n! ]4 }! s2 Z. Z* n
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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.TVBNOW 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。, P. U& B7 i0 K$ G) H* p
- ]* Z: J3 _9 y. D% OA 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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Blobs of magma occasionally break off from the top of the plume, and rise farther, resupplying the magma chamber beneath the Yellowstone Caldera.( @1 Z2 t; o$ ~$ s9 x, k
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6 [% r5 L) t+ I" X( Z; ^# Stvb now,tvbnow,bttvbSteaming Mud Volcano at Yellowstone National Park in winter. Researchers now believe that the supervolcano beneath the park could be more active than thought TVBNOW 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。3 r% o$ n2 f4 E7 K
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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 uninhabitable7 S: v5 L. q) a9 w# {/ ~' Y' v* o$ c
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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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4 r# {8 ^+ Y q% T& k" Qtvb now,tvbnow,bttvbResembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.公仔箱論壇8 `8 I8 B: J, v0 ~4 k8 T
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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+ x0 g# X4 n: \8 j( X
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: Z. K' [, O- Q* {% V+ lA full scale eruption at Yellowstone would be 1,000 times more powerful than the volcanic blast that tore apart Mount St Helens in 1980.
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& _# d. i# d5 Z! R公仔箱論壇There is evidence that a similar super-eruption in Indonesia 74,000 years ago came close to wiping out the entire human species.公仔箱論壇2 g% u5 R. P' W8 N _0 Z, m
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The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.5.39.217.76( v) W% Q& Q- q& W% P( F
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' j9 d0 s6 D/ ~+ v% k0 A+ s$ SSeveral 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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The 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.TVBNOW 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。+ l' f9 A2 h% g' S9 S
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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.
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3 ^! q" y6 F" |% q: W# a0 l‘The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem.’
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9 F0 ?8 F+ v0 E( n3 k! U" e- C+ }TVBNOW 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。
! T5 T3 g0 T+ g6 h3 k2 Ktvb now,tvbnow,bttvbHe 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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