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( |! Y% A, d2 E7 O8 F3 [+ \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。- 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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Instead of the process taking hundreds of thousands of years, it could take just hundreds.
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6 O" { |/ \# `1 `- JThe 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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5 H; d5 j2 Z5 V- X% v6 l" L, x公仔箱論壇Eruption: Supervolcanoes with the power to destroy human civilisations may build up a deadly head of steam far faster than scientists believed
6 Q0 Z& ?* V9 ^. m5.39.217.76Supervolcanoes are fuelled by giant pools of magma that form deep underground.公仔箱論壇& j2 u. t, H) M; l0 S: O
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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.! L6 i$ d9 r' {& \
9 r2 b# v# g u9 a6 c) `+ ?- s0 Ytvb 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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- A# ~$ m' R- H5.39.217.76A 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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Blobs of magma occasionally break off from the top of the plume, and rise farther, resupplying the magma chamber beneath the Yellowstone Caldera.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。& ?8 F/ N+ D2 {
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. a5 l4 m5 b8 x) o7 b/ n# i5 t7 X) _5.39.217.76Steaming Mud Volcano at Yellowstone National Park in winter. Researchers now believe that the supervolcano beneath the park could be more active than thought tvb now,tvbnow,bttvb+ K' o9 p4 s) ~ v: Q$ [6 L* 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。( A7 ^9 F( z9 d9 u" T( K
/ ^, k/ R: ]5 C, o/ [9 U( V. v6 r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
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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- U$ N* z" H/ W9 a9 [5 U
5 Y( U8 d! H4 t h6 u) bTVBNOW 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。Resembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.
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1 h) h7 P- m3 K# I5.39.217.76The supervolcano has erupted a total of three times in the last 2.1 million years. Scientists believe it could be due to erupt again.1 M4 S6 i5 r8 S: a
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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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8 o0 r0 D6 D( U% ^5 q9 s- W5.39.217.76There is evidence that a similar super-eruption in Indonesia 74,000 years ago came close to wiping out the entire human species.
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The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.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。/ H+ Z: n0 h- I( O" y: Y
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- [1 I& t' \/ a2 J! XSeveral 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.) m/ u1 s9 ]. X+ x
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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.
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+ z! f. h; P& cThe research is published in the online journal Public Library of Science ONE.
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' X, S, U% D& d$ w5 ?tvb now,tvbnow,bttvbLead 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.’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。* [+ M% R8 u$ B) B* V- t
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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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