Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now
- R4 ]3 G3 L4 h; [1 x3 o, T- 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. tvb now,tvbnow,bttvb l* f4 F0 A) ?; c+ _
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Instead of the process taking hundreds of thousands of years, it could take just hundreds.9 }$ Y7 J0 A6 X% r7 r6 K. I
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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.
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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 believed5.39.217.767 a( `* \! x, t2 W$ O7 ^+ X* x
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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, a1 `3 X, ?! Q- Z+ S. d! Z5.39.217.76But the new study suggests that the giant magma bodies may only exist for a few thousand years, or even a few hundred, before exploding.! k; `5 ^; c# u/ c: t
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A magma reservoir six miles below Yellowstone has been rising at a record rate since 2004.
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& l$ |$ @# t- t/ }4 G+ a5.39.217.76The 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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$ q# {7 S5 l4 X6 _. M' }5 dBlobs of magma occasionally break off from the top of the plume, and rise farther, resupplying the magma chamber beneath the Yellowstone Caldera.3 ?/ {, U& s/ t
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h" P4 P4 X7 M. E5.39.217.76Steaming Mud Volcano at Yellowstone National Park in winter. Researchers now believe that the supervolcano beneath the park could be more active than thought . t s$ d R* B8 K
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# G/ b0 q; X# Z7 J M5.39.217.76The 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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* k! O4 g; ]/ s p- PTVBNOW 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。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.tvb now,tvbnow,bttvb. E& {3 M8 f6 q; @8 x$ }
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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.% J8 M5 |4 r/ w0 u8 _0 L6 u% A
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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.
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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.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。7 T4 X( j ^! N' O
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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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4 e/ {% F; W6 ^5 n( F8 T; t- m& M! ntvb now,tvbnow,bttvbThe 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.公仔箱論壇. R* s: K# Z! O7 C0 r$ O( {
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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.0 O! @1 ^9 E, A& t
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" f3 y2 v$ q! R‘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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3 U- ] K8 p2 R- I7 v. Ntvb 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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