Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now
$ N; G* {( p: ?9 y( H( t2 P, vtvb now,tvbnow,bttvb- 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. ) x) S8 i0 J' @. U' d
2 Y: [9 x2 ]; o5 x* t7 Q9 jInstead of the process taking hundreds of thousands of years, it could take just hundreds.
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9 `) [" ~) { U5 e# P& |5.39.217.76The 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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Eruption: Supervolcanoes with the power to destroy human civilisations may build up a deadly head of steam far faster than scientists believed# [7 {3 }! t2 n% j2 e
Supervolcanoes are fuelled by giant pools of magma that form deep underground.公仔箱論壇5 j k+ R0 f. \. L
/ A$ a3 s/ A+ f5.39.217.76Geologists 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.
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' q. ?, E! b f- A1 \1 TA magma reservoir six miles below Yellowstone has been rising at a record rate since 2004.3 m- ^+ B2 N3 ~& t
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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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* i* b/ h! }7 Y5 Q+ y8 k7 X6 JSteaming 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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3 }% R0 @# f$ o' f) S4 u; ~, eThe 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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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( ?+ x3 R6 j* W, |. m3 u
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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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/ B( ^% }) v( b- G" A& SThe supervolcano has erupted a total of three times in the last 2.1 million years. Scientists believe it could be due to erupt again.公仔箱論壇1 ~. O+ Y) F% S# [" d
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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.tvb now,tvbnow,bttvb3 X, j Q" t" N0 z$ l2 J$ d
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) d% g0 i* o7 z! ?) c1 f; jThe new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.7 L% V; r- r ^7 e Y
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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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/ p6 E6 O# c* i; {; p% h4 z; g5.39.217.76The 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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4 x0 I% E& c. Z- ]公仔箱論壇The research is published in the online journal Public Library of Science ONE.- Z$ ]9 H& r8 U, c( D' p$ [! `
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" ^9 e+ K3 E; l4 o# D9 HLead 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.tvb now,tvbnow,bttvb! Y4 m* V1 T6 H
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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.’; D' L, y$ n( r9 h* t* {$ J
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- M# z; u+ N$ Z8 ]9 r9 q! e) k: _9 ITVBNOW 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。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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