Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now5.39.217.76- S7 _! f4 |3 ?: o9 R
- 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.
0 S# s0 B' n- A) l+ R8 h8 j/ \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.
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* R' {4 `4 N7 V6 u+ n* e+ L, v1 HThe 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! J5 V+ [6 C+ l7 L
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.
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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。/ q" s3 L0 l! o. I
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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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Blobs of magma occasionally break off from the top of the plume, and rise farther, resupplying the magma chamber beneath the Yellowstone Caldera.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 c. a/ G& Y, |+ n
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Steaming 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。, h+ H k" A" n7 a0 a) ?6 ^, E5 G: j
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) d& J5 t7 R2 S* H4 @( [: m' Ltvb now,tvbnow,bttvbThe 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 uninhabitable5.39.217.767 L6 z2 m! q: }, r S; y$ M6 ^1 Z
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' l- I' f* L& k; A, A公仔箱論壇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.5.39.217.76/ |; P6 i+ Q' W
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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.
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. y* ]7 D& l. P4 `( X7 ~A full scale eruption at Yellowstone would be 1,000 times more powerful than the volcanic blast that tore apart Mount St Helens in 1980.3 l$ h2 h" n. F c
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8 h3 F' v7 e3 etvb now,tvbnow,bttvbThere 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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; C' ]! }: D$ n6 v. u0 H% i( t( I5.39.217.76The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.
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2 L) ^/ T( U8 d7 {. D公仔箱論壇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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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.' W$ j7 T# {. ]8 x( @* {
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The research is published in the online journal Public Library of Science ONE.
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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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‘The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem.’! _- H R0 e( N/ i
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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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