Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now# J" U [* ?2 j: v. S1 @8 A
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.
7 T4 K& ^: v$ D5.39.217.76A '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. ; t6 E) V9 T' C3 [: s! v
; c2 R$ m3 v7 F9 h& l; C) Q5.39.217.76Instead of the process taking hundreds of thousands of years, it could take just hundreds.2 |$ [" M/ L% g, ~4 E9 M
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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. 1 i* D4 S( ^ M4 c/ T+ s1 b M: Htvb now,tvbnow,bttvbTVBNOW 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。! P# ?$ n: k/ Q# l& y 5.39.217.761 l2 j' B5 \5 Q9 } @ W2 N
Eruption: 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6 O1 x3 h h: v
Supervolcanoes are fuelled by giant pools of magma that form deep underground. 8 c* v% s! m* Y' u5 t" X) Ctvb now,tvbnow,bttvb ! V# Z- G, X/ A& y( [公仔箱論壇Geologists had thought it took between 100,000 to 200,000 years for a supervolcano magma pool to build up enough pressure to erupt.公仔箱論壇% r' a# {4 O3 K3 J( P7 d$ ^
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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. 2 V E" d3 r, U+ y公仔箱論壇 8 B3 k: u8 E. T/ Jtvb now,tvbnow,bttvbA magma reservoir six miles below Yellowstone has been rising at a record rate since 2004. ( b6 N) E, ~4 |+ atvb now,tvbnow,bttvb $ F7 o* c( ~6 s/ N3 z6 b& x6 TThe 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. ! K" T) j' h, C" c+ ~6 {tvb now,tvbnow,bttvb7 m V# P' j* \; f" y& f2 U
Blobs of magma occasionally break off from the top of the plume, and rise farther, resupplying the magma chamber beneath the Yellowstone Caldera.: n1 Q9 W2 h; A- v5 Z
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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 公仔箱論壇! O1 F) b% E) ?" e9 f3 `* l
" p- ?0 U# Z+ x: ytvb now,tvbnow,bttvb # |; }6 U. Z6 cThe 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。7 @2 ]' q5 \/ Q9 c& p* K7 d
# E% D. \8 o* Q% W6 H% Z W9 D* dtvb now,tvbnow,bttvb % c" K. {; D! R" o; n: z9 _4 g1 ZCastle Geyser and sunrise Yellowstone National Park Wyoming: Researchers now believe that the huge 'supervolcano' beneath the park is far more active than previously thought 3 ^+ G& N/ Y9 B0 k5 g2 I ; T, ]; }, f: Q6 ]# Rtvb now,tvbnow,bttvbResembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.公仔箱論壇% l' w( i) r2 t+ T, ?
8 o' |+ W3 n, x& K5.39.217.76 ( W1 D( z M5 K1 QThe supervolcano has erupted a total of three times in the last 2.1 million years. Scientists believe it could be due to erupt again.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 A1 y( D4 s5 c, x/ I$ D
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) K. c* @5 V ]) I9 e公仔箱論壇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.tvb now,tvbnow,bttvb0 d. ~; B+ x( [% E
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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. % ]* w3 |" E; A' C7 [ H, _" w' K1 P8 c! J0 q$ w ' R) l8 g* V3 {' x" r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. }- P8 `. k& l+ d8 N! W2 C公仔箱論壇tvb now,tvbnow,bttvb8 @3 o+ ~+ R5 m1 y/ w8 Z0 l
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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. ?& F8 s' v( q( y& C& g& { Y. N5.39.217.760 v7 H7 F, q# E! S5 T1 b
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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. ; `' _ O% H' _9 R, ^0 I6 t公仔箱論壇6 H* P2 D2 w2 j/ [& O) p% ~
/ Q: q$ a" P4 P& W8 u公仔箱論壇The research is published in the online journal Public Library of Science ONE.tvb now,tvbnow,bttvb8 T2 I! X, J: n& z- \) a
8 K& }" [1 W" `( U. v I5 }6 R3 c* w% r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. + V$ {8 \% ]; Z9 T: \) `1 N5.39.217.765.39.217.760 b- I- x5 ~" {
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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.’ ; J3 E- W& J! q' G( k0 R7 E5 {5.39.217.76 5 G* t6 [* ^5 I* W4 a6 N ) q# ^- A, J: ?4 S, Y, DHe said regions such as Yellowstone should be monitored regularly to provide advance warning of a catastrophic super-eruption.作者: cms 時間: 2012-6-1 08:11 PM
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