I am attaching the document needed to do the assignment. Answer should be at least 250 words not including headings and etc.Describe the type of volcano that is being studied in this article. How does it behave? What extinct (hopefully!) volcano closer to home might erupt the same way?
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An Icelandic Volcano Reveals Secrets of Its Eruption
By HENRY FOUNTAIN JULY 14, 2016
A plane flying over the Bardarbunga volcano spewing lava and smoke on Sep. 14, 2014. Credit
Bernard Meric/Agence France-Presse Getty Images
Some of the worlds most cataclysmic volcanic eruptions are associated with the collapse of a
caldera, a depression in the top of the volcano that forms and deepens as a reservoir of magma
below it empties out.
The two largest of the 20th century Pinatubo in 1991 in the Philippines and Novarupta in
Alaska that formed the spectacular Valley of Ten Thousand Smokes in 1912 both blew their
tops this way.
Caldera collapses are rare, and when they do occur they usually happen quickly, in hours or a
few days. But when Bardarbunga, a large volcano under an ice cap in central Iceland, erupted in
August 2014, the caldera sank and collapsed gradually over the course of the six-month eruption.
That gave scientists a unique opportunity to study it.
In a report published Thursday in the journal Science, volcanologists reveal that the sinking
caldera actually helped drive the eruption, by keeping pressure on the magma chamber as the hot
rock flowed out.
We are talking about a hydraulic system, said Magnus T. Gudmundsson, a researcher at the
University of Iceland and lead author of the paper. The caldera, he said, pushed down on the
reservoir of magma, which flowed nearly 30 miles through a fracture in the volcano before
emerging at the Holuhraun lava field.
Because the caldera collapse happened under the Vatnajokull ice cap, which is about 1,500 feet
thick on average, Dr. Gudmundsson and his colleagues had to study it indirectly using
seismometers, radar and other instruments. They also placed GPS sensors on top of the ice,
which enabled them to gauge the collapse of the caldera because the ice followed it as it sank.
The caldera is roughly oval in shape, covering about 40 square miles, making the collapse the
largest ever monitored. Over the course of the eruption it sank about 200 feet.
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Dr. Gudmundsson said the research showed that the eruption started when pressure increased
within the magma chamber, which is at a depth of about seven miles. The caldera collapse began
about five days later, when an estimated 12 percent to 20 percent of the magma had already left
If the collapse had not started, Dr. Gudmundsson said, the eruption might have ended at that
point because the loss of all that magma had reduced the pressure in the chamber. But the
collapse put new pressure on the chamber, and the flow of lava continued.
The caldera, he said, is like a piston pushing down on a body of fluid, and there is a pipe going
from this container of fluid sideways to the surface.
John Stix, a volcanologist at McGill University in Montreal, said the Bardarbunga findings were
fascinating for what they showed about the mechanics of the collapse. One would think that
calderas dont collapse like pistons, he said. But effectively thats whats happening.
He said the study would help scientists better understand what drives extremely large eruptions
like Tambora in what is now Indonesia, which led to what became known as the year without a
summer when it erupted in 1815.
Dr. Gudmundsson noted that scientists did not notice that the Bardarbunga caldera was
collapsing until about two weeks after it started. That would not happen today, he said, thanks to
this research, which identified the kinds of seismic signals that indicate the start of a collapse.
Thats very important to know, Dr. Gudmundsson added, because not all collapses are as
gradual and well behaved as this one.
For instance, if Yellowstone were to erupt again it would no doubt involve a collapsing caldera
and be far more catastrophic than the one observed in Iceland. Despite some of the hysteria about
Yellowstone, which last erupted 640,000 years ago, the odds of another eruption happening
anytime soon are vanishingly small.
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