Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now
, w2 z2 X7 d+ L3 {3 d) G- 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.
: z: a; Y2 ?" H# ?4 s5.39.217.76A '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. + C y7 O. p! k4 c9 G; F
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Instead of the process taking hundreds of thousands of years, it could take just hundreds.6 i: H! b8 k! [" F7 q
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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.tvb now,tvbnow,bttvb3 T6 y% u- G6 U) y! J/ P7 D9 Y
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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 believed5.39.217.76) R2 Q5 o& v/ P
Supervolcanoes are fuelled by giant pools of magma that form deep underground.3 G& \# W( j# ]* ?$ R
3 C/ H) L( M, L# A3 S$ `2 i5.39.217.76Geologists had thought it took between 100,000 to 200,000 years for a supervolcano magma pool to build up enough pressure to erupt.5.39.217.76) F9 _$ D" l$ u' v
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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.tvb now,tvbnow,bttvb3 d- J; o9 R. k! H+ f
+ \& U) c6 s5 N% |$ ^( ktvb now,tvbnow,bttvbA magma reservoir six miles below Yellowstone has been rising at a record rate since 2004.tvb now,tvbnow,bttvb- f( }9 n9 J5 U. e, X
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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.* ^1 Y" e' L: L+ y. x, L9 y
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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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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 uninhabitableTVBNOW 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。& S q/ y6 H0 Q# k
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, Y2 f' ?( K+ `: g1 tCastle 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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' A6 F$ w( d' S L" V2 {tvb now,tvbnow,bttvbResembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.
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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.tvb now,tvbnow,bttvb; Y" f. L- X& {) z7 i
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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,bttvb* Q& }/ P/ l/ c; ?/ Y3 U& q
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- T1 C' o- [2 A5 p; y# c1 WTVBNOW 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 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.tvb now,tvbnow,bttvb( E- k @% R: \" A5 V5 k, w
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4 ?7 c/ z9 W& W8 `* H2 A0 c- ytvb 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.
9 k& C8 |+ @5 _$ e! u5 e: v- nTVBNOW 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。# D/ h$ O" N6 B. x8 X3 |: x
4 u$ z+ O. W+ o& k; x; }5 R& R公仔箱論壇The research is published in the online journal Public Library of Science ONE.4 L* ]; N, o/ Z" A2 `, M* x) d! [+ c! ?
9 V1 D0 G, a5 h# O( R: a lTVBNOW 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。
$ @, i+ l! j; o$ G% G. }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。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.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。) g8 _ [" [+ O- a( s
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& ]$ C4 c7 c7 M2 }( I3 X‘The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem.’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。) x' V) H7 m1 F1 d; D
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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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