Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now& i/ e# Q# D$ n
- 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.
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2 V0 F |) Z) h5 ?: c, p5.39.217.76The 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.( O* u& f7 _. |% L5 |! H J
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4 Q. k k2 z6 {( w# ftvb 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- i/ d' E3 F) f
Supervolcanoes are fuelled by giant pools of magma that form deep underground.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。' o1 K5 m ^; g4 z9 d
% T. f* c) ^" |' M3 utvb now,tvbnow,bttvbGeologists 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.5.39.217.76! T; H7 @: E( A* G7 C# u# 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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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.
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$ u+ J3 y+ \9 _4 f. G o& n5.39.217.76Steaming Mud Volcano at Yellowstone National Park in winter. Researchers now believe that the supervolcano beneath the park could be more active than thought
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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 uninhabitable5.39.217.761 b1 V* Z$ \9 J
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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.
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2 m+ ]4 h. B1 ?& e( hTVBNOW 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.4 a# E) v2 W; N" i! {% P `, ~
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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 1980.5.39.217.762 S2 q: k; j! ~" j
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# \2 F1 b+ K! h" e: o/ H/ D% 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。There is evidence that a similar super-eruption in Indonesia 74,000 years ago came close to wiping out the entire human species.5.39.217.76# ?+ H; w! D% g1 a6 `1 B
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$ Y; x1 A; ]3 j# T& y6 n2 T% M+ _7 WThe new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago." O( z4 _" b, \5 s. E9 A+ R% |9 B
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/ j/ J7 X. Y! |/ s* ]6 P4 Ktvb now,tvbnow,bttvbSeveral 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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T6 B$ n# w2 U5 S; V; GThe research is published in the online journal Public Library of Science ONE.
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: a, g$ ]& J& R0 c! K9 A: Q. u, O公仔箱論壇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.’tvb now,tvbnow,bttvb `2 }9 G$ i' A \0 o/ V9 z
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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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