Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right nowtvb now,tvbnow,bttvb8 K/ C) e$ [2 S) Z& U+ O
- 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. 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。0 W+ I( G( E# K: |. l; p
B# f$ a: b+ @, xTVBNOW 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。Instead of the process taking hundreds of thousands of years, it could take just hundreds.
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: I0 G4 C, C2 B1 z, I1 o+ y公仔箱論壇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." l3 o( r& t7 b( ^+ y/ r
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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
- j! s5 ^$ Q5 t/ [0 R- w# ywww2.tvboxnow.comSupervolcanoes are fuelled by giant pools of magma that form deep underground.公仔箱論壇, o7 q% {( K4 g: z$ y# W
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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.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。, I8 z9 A) r" W1 k* }
* Z4 ]6 }& Z5 l- N7 jtvb now,tvbnow,bttvbBut 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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% ]4 o+ V [% I* ctvb now,tvbnow,bttvbA 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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, V( K" N+ u( P3 q/ [% E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.公仔箱論壇; Y3 M! l! R& X7 Z# e/ o7 N# k- B- W
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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
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1 G, v0 E- J& fwww2.tvboxnow.comThe 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 thoughttvb now,tvbnow,bttvb/ I8 x* B2 D0 }% J6 g) N9 t% h
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Resembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.3 G" `3 o/ s$ J; a1 l
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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.公仔箱論壇( w _4 s1 W" v, R$ H* Z
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+ b2 a$ m1 ^5 p0 \" G7 Z; \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.www2.tvboxnow.com. I% |2 |9 m, m) _( q
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/ b8 K7 Y% U) }. w! u9 V3 }6 b公仔箱論壇The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.
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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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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.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。9 m/ v$ _4 _5 S
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The research is published in the online journal Public Library of Science ONE.公仔箱論壇: N4 @" J* K( D; a6 p/ B
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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.’
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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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