Supervolcanoes with power to 'destroy civilisation' explode far more rapidly than scientists had believed - and one could be bubbling under U.S. right now
- {1 Z* U. f7 V6 t7 Q' Y' A公仔箱論壇- 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. 5.39.217.76- @" M3 K$ ~: m5 ^; [
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Instead of the process taking hundreds of thousands of years, it could take just hundreds.tvb now,tvbnow,bttvb. Z& m) z. D0 B/ L2 G
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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.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。" Q1 H0 X0 d! ?; [8 |! j4 @& o; Q
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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 f1 u! B, B z% _
Supervolcanoes are fuelled by giant pools of magma that form deep underground.5.39.217.76) B1 r2 [" E$ u! l) Q/ x
. J8 z' y; K0 [6 wtvb 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.
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' U1 f# F: v; H) I) G% ^$ q5.39.217.76But 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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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.1 s4 K) f( ^, I/ D9 [
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w! h; q- Y0 ]) m6 O2 t5.39.217.76Steaming Mud Volcano at Yellowstone National Park in winter. Researchers now believe that the supervolcano beneath the park could be more active than thought ( R# W: l' f: X- J* `; w3 N$ @) H
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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
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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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4 i/ J4 n/ r& n& O# Ttvb now,tvbnow,bttvbResembling the lid of a cooking pot, the caldera formed when the last super-eruption occurred 600,000 years ago.5.39.217.763 B. ?3 \* R0 C" _6 S
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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.
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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.& c& z# k, a" d0 G
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The new study was based on analysis of a super-eruption that occurred in eastern California 760,000 years ago.tvb now,tvbnow,bttvb$ J4 D: q o e# x9 _) R
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7 b8 n& H4 T, H0 Y' m+ Ctvb 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.2 @! ^8 ^3 d, S( g1 U
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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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. `/ m* M2 {3 T- L3 m8 G. yTVBNOW 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 research is published in the online journal Public Library of Science ONE.: K* m. p( F- V5 E$ s% B) f
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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.tvb now,tvbnow,bttvb7 g: ~. Z& ~& o/ T- }% R+ U
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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.’tvb now,tvbnow,bttvb: ~4 r5 e' P4 s7 l- P
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3 a2 g6 k: j9 x7 {2 z& |* }5.39.217.76He 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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