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,bttvb' D: N; `3 A: [" H C) X7 \' F
- 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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; f# N) h$ F2 e. [2 _2 V0 S) ^公仔箱論壇Instead of the process taking hundreds of thousands of years, it could take just hundreds.5 m# B6 f" a5 u$ P% \7 s4 ?2 o
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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.- q* ~2 O+ T- F: Y/ U; [% ]1 K
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+ C+ s# a# x+ O; r" P/ eEruption: Supervolcanoes with the power to destroy human civilisations may build up a deadly head of steam far faster than scientists believed
5 Q9 _, A$ }7 b6 O6 B0 P- l# n5.39.217.76Supervolcanoes are fuelled by giant pools of magma that form deep underground.
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) L! |+ W, n# ]tvb 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.# k! @# d8 L$ y2 g
3 _# T( E0 \5 s3 ^* F; mBut the new study suggests that the giant magma bodies may only exist for a few thousand years, or even a few hundred, before exploding.' V! F) ^" J* R2 x9 U; I
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A magma reservoir six miles below Yellowstone has been rising at a record rate since 2004.
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; m% z% P+ o' F: C+ x) R( g2 ~5 f5.39.217.76The 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.公仔箱論壇% k4 V- s6 y x" x: [* q l
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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 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。( C, a1 {* U( @ v8 R ^# L; `3 |
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. M2 a6 V7 t! 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 uninhabitable
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R) G8 U- M; y1 K @" 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. X, K& O5 [3 Y0 D8 a" P4 O
+ ~0 J5 C; u3 I, H/ M$ }1 LResembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.tvb now,tvbnow,bttvb5 I2 G. g p( p: I- R- x% t |, `
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% O: M0 i( b0 k# d9 B# ` r公仔箱論壇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.
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8 R7 R+ d# C7 @( a7 J% O+ i$ A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.
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0 ~3 @" X. u$ Z* a8 Xtvb now,tvbnow,bttvbThere is evidence that a similar super-eruption in Indonesia 74,000 years ago came close to wiping out the entire human species.# ?/ [8 w' t4 v& j% v% y
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' W; p, _, P5 ?# W6 i4 N; k' f( 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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% B. b+ C' q" L# z& Z! V1 \; W- dtvb 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.公仔箱論壇. L/ Y. u" i' S' X% e
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6 x- ?7 o# W4 R5 U) l: D$ F/ ^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。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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# O$ V5 q5 \; D9 j, ?5.39.217.76The research is published in the online journal Public Library of Science ONE.
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* ~0 F8 t% O' F) Y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.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 h! z9 P5 i7 E/ i4 m7 X( {
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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.’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。5 t( U, L7 l$ m2 h5 S
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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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