Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now
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- 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.
% }3 t& L/ e$ {) _1 g5.39.217.76A '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.
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Instead of the process taking hundreds of thousands of years, it could take just hundreds.
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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.5.39.217.764 U& d }9 D0 b4 _, _8 H
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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 believed3 u( \- s8 F) H0 ~
Supervolcanoes are fuelled by giant pools of magma that form deep underground.
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" i5 \! _' O1 w, I8 Q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.
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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.
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A magma reservoir six miles below Yellowstone has been rising at a record rate since 2004.
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5 ~$ a- c: R% ]8 C" Vtvb now,tvbnow,bttvbThe 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.
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6 {& _/ K& |, ]" A8 ySteaming 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1 u2 r, W$ Z6 w7 T5 R& L' J! N
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1 C9 D( F; y& Ntvb now,tvbnow,bttvbThe 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 uninhabitable5.39.217.76+ [6 [8 @( R; W- L1 V' c2 l2 B
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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
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Resembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.
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8 ]: ~4 w8 V/ r, VThe supervolcano has erupted a total of three times in the last 2.1 million years. Scientists believe it could be due to erupt again.: z3 d1 O1 K0 m
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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.4 S: d1 T5 s2 |% n) k" y
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The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.& T z! d1 }( d
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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.5.39.217.76( O$ v7 h, Y( H& e8 a9 ]+ s
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3 C9 `7 d' h- D. e* j. _5.39.217.76The 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.+ F4 F% p) ^% v8 D! V$ q2 K W
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" F2 p& M6 c! P! k5.39.217.76The research is published in the online journal Public Library of Science ONE.
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. c. _7 Q0 m8 {6 L5 b$ I. gLead 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。- f* a! V8 z6 K/ _. Y
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7 B& ]$ e# b5 c: b公仔箱論壇‘The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem.’: r1 q1 j. t8 k; k0 Q9 O7 S3 @& Q
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5 b' x+ T& o/ uHe 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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