Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now; P# Y2 |- t! X
- 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.
) r3 t6 L7 [. }2 mA '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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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.公仔箱論壇+ N9 v7 c' x& Z+ d) E9 t) a
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' Z. }( ^9 t: H. g$ \3 f, X( h8 Z/ ]9 Gtvb now,tvbnow,bttvbEruption: Supervolcanoes with the power to destroy human civilisations may build up a deadly head of steam far faster than scientists believed公仔箱論壇* E. _+ ]0 ~. b5 B7 N( J1 J$ t
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.tvb now,tvbnow,bttvb+ `( K9 d- {6 n( I. W
, Z( h2 K* j! U$ zBut the new study suggests that the giant magma bodies may only exist for a few thousand years, or even a few hundred, before exploding.tvb now,tvbnow,bttvb, S; i1 T+ z4 M* R
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A magma reservoir six miles below Yellowstone has been rising at a record rate since 2004.
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5 C* L/ B& y7 V' p! x) u2 e公仔箱論壇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.公仔箱論壇3 m& s0 @) k" U. ^& V9 |. \
- y% Z }3 U3 _% k4 L+ g7 ?$ Q$ H公仔箱論壇Blobs 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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; U0 Y) ^ R3 H. |0 w6 }公仔箱論壇Steaming Mud Volcano at Yellowstone National Park in winter. Researchers now believe that the supervolcano beneath the park could be more active than thought
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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
5 _( i, y4 E1 V2 cTVBNOW 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。
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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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/ D- s0 J# W" I! K5.39.217.76Resembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.
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, a/ l6 ]$ \+ u8 ]5 r% r) [+ \) DThe supervolcano has erupted a total of three times in the last 2.1 million years. Scientists believe it could be due to erupt again.. y+ N! _4 `3 k3 z
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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 1980.5.39.217.76( [$ B7 x/ t6 q0 x% _$ q; y; ]$ V
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( T8 l7 Z% k# G: Ntvb 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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- q p) w }$ \5.39.217.76The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.
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5 |" B) d+ i% }; B: H2 ESeveral 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.5.39.217.76% n8 ]8 }# M0 u' u! ?; o
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# y- o" ]3 H9 o7 JTVBNOW 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 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.. I7 d* x! a/ W4 C, X
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0 v1 I, w- n4 Z( ^7 aLead 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.公仔箱論壇& }: Q* P- A. d8 Z6 R* d# }" ~
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$ O% w# w( |2 ?5 ?1 K; htvb now,tvbnow,bttvb‘The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem.’
& U; |' F" j8 g% x( Z* I1 d4 \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。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。& L4 v/ o- n" K8 F5 ~
% c; ^- Z6 h) w: hHe 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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