On Feb 3, 6:58 pm, Travis <baconl...@gmail.com> wrote:
> Concerns grow over volcanic eruptions****
>
> By Elizabeth Weise, USA TODAY****
>
> http://www.usatoday.com/tech/science/environment/story/2012-02-01/dea...
> ****
>
> Published: 2/1/2012 7:52:20 PM****
>
> Scientists have known for decades that hidden under those impressive vistas
> at sites such as Death
> Valley<http://content.usatoday.com/topics/topic/Death+Valley>and
> Yellowstone
> National Park<http://content.usatoday.com/topics/topic/Places,+Geography/Parks/Yell...>are
> magma pools that under the right conditions can trigger explosive
> eruptions.****
>
> Now, new research is changing scientists' understanding of the timing of
> those eruptions, and prompting them to call for greater monitoring of sites
> to help save lives when the next big volcano explodes.****
>
> Two recent papers highlight the shift. One looked at a Death Valley volcano
> thought to be 10,000 years old and found it last erupted just 800 years
> ago, and is still an eruption danger. The other found that large caldera
> volcanoes, such as the one under Crater Lake in Oregon, can recharge in a
> matter of decades, rather than the thousands of years previously thought.***
> *
>
> "The understanding of the timing of eruptions and the timing of the
> building up to eruptions is changing," says Margaret Mangan, the scientist
> in charge of volcano monitoring in California for the U.S. Geological
> Survey<http://content.usatoday.com/topics/topic/U.S.+Geological+Survey>.
> "These two papers are very nice examples of good scientific work."****
>
> One thing that's coming to light is that eruptions are often clustered,
> with "long stretches of inactivity punctuated by periods of activity that
> can go on for years," Mangan says.****
>
> The first paper looked at the Ubehebe Crater (you-bee-HE-bee) at the
> northern end of California's Death Valley. It's about half a mile wide and
> 700 feet deep. It was long believed to have been caused by a volcanic
> eruption sometime in the past 10,000 years or so.****
>
> However, researchers recently looked at beryllium in the rocks and were
> able to date the last series of eruptions to just 800 years ago. They say
> the ingredients necessary for another eruption are all still there.****
>
> Ubehebe Crater is the result of what's known as a phreatomagmatic
> (free-at-oh-mag-MAT-ick) eruption. That means that it has a huge pocket of
> molten rock, or magma, deep below it. When it begins to push to the surface
> and comes into contact with water, superhot steam is created, building up
> pressure until it explodes.****
>
> It had been thought that the eruptions would occur only during wet climate
> periods, and as Death Valley is famously dry now, there was little concern.
> But using U.S. Geological Survey data, the scientists show that the current
> water table may be just 500 feet below the surface of the crater. The paper
> was published this month in the journal *Geophysical Research
> Letters<http://content.usatoday.com/topics/topic/Geophysical+Research+Letters>
> *.****
>
> The relatively recent eruption means that the magma underground, which can
> take thousands of years to cool, is likely still hot. When water and hot
> magma come into contact, it can produce something "like a very large bomb
> going off," says Brent Goehring, a geochemist at the department of Earth
> and Atmospheric Sciences at Purdue University in West Lafayette, Ind., and
> one of the paper's authors.****
>
> Another worry is that caldera volcanoes, such as Mount Pinatubo in the
> Philippines and Krakatoa in Indonesia, may be able to blow much more
> quickly than previously believed.****
>
> Caldera volcanoes consist of large underground lakes of magma. As more
> magma builds up, the pressure builds and the magma starts getting pushed
> upward through cracks in the Earth's surface. When the pressure gets too
> great, it explodes.****
>
> Caldera volcanoes typically have a long quiet period prior to eruptions.
> Writing in Wednesday's edition of the journal *Nature*, researchers looked
> at the eruption of the Santorini volcano in Greece around 1,600 B.C., which
> released as much as 12 cubic miles of magma.****
>
> By analyzing feldspar crystals formed within the magma and then ejected
> during the eruption, the researchers found that the volcano's magma chamber
> grew by as much as 10% in the final few decades before it blew, says Tim
> Druitt, a volcanologist at Blaise Pascal University, Clermont-Ferrand,
> France, and senior author on the paper. ****
>
> For this reason, scientists are calling for greater monitoring, including
> satellite surveillance, to detect ground swelling.****
>
> There are several large and still active calderas in the United
> States<http://content.usatoday.com/topics/topic/Places,+Geography/Countries/...>,
> including the one under Yellowstone National Park. All are closely
> monitored. What worries the researchers are other unmonitored calderas
> around the world with the potential to send huge clouds of ash into the
> atmosphere, causing massive ecological and climate damage.****
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