Earth contains many varied landscapes and features such
as mountains, plains, deserts, jungles, and waterfalls. Perhaps one of more
fascinating features is volcanoes.
Often formed by converging or diverging tectonic plates or
mantle plumes, volcanoes are openings where molten rock, ash, and gases escape
from beneath the Earth's crust. A BBC documentary in 2000 also popularized the
term "supervolcanoe," which refers to "explosions of exceptional violence and
volume".
In this month's National
Geographic, one of the United
States' most famous National Parks is
discussed. In the article "When Yellowstone Explodes," the author talks about
how the park is seated upon one of the largest volcanoes on Earth and what it
would mean should the Yellowstone caldera
erupt again.
"Volcanoes Form
Mountains; Supervolcanoes
Erase Them"
According to NatGeo,
the "hot spot" that caused the Yellowstone
caldera (from the Spanish word from "cauldron") has erupted dozens of times for
more than 18 million years. The tectonic plate associated with the hot spot is
moving southwest, but ancient explosions are reportedly strung across southern Idaho and into Oregon
and Nevada.
The last three known super-explosions have occurred in Yellowstone
National Park, with the "most recent" one dating back 640,000 years ago. Though
scientists cannot be positive, they calculate that the ash from the last
explosion reached 100,000 feet, leaving debris all over the American West and
all the way down to the Gulf of Mexico.
Pyroclastic flows are estimated to have reached 1,470 degrees Fahrenheit.
While it sounds impressive, that eruption was considered
tame compared to the one 2.1 million years ago, which left a hole in the ground
the size of Rhode Island.
Not Extinct, Afterall
In 1870, Lieutenant Gustavus Donane completed an exploratory
expedition of the Yellowstone Region and claimed, "The great basin has been
formerly one vast crater of a now extinct volcano." His belief was accepted for
decades before Francis Boyd, a Harvard graduate student, realized that the
presence of a welded tuff – a heated and compacted ash that he'd been studying
- was a sign of pyroclastic flows from a recent eruption.
Another researcher, Bob Christiansen, and his colleagues
later discovered a second and third welded tuff. Christiansen's team used
potassium-argon dating to discover that the three tuffs belonged to three
distinct eruptions – each that created calderas, which were later buried by the
most recent eruption.
"The Living,
Breathing, Shaking Caldera"
Later, in 1973, yet another researcher named Bob Smith and a
partner noticed that trees along the South Arm of Yellowstone Lake were
partially submerged and dying. Curious, Smith began to resurvey benchmarks set
by past workers begun in 1923. The results of this survey found that the Hayden Valley
at the north end of the lake had risen over 30 inches throughout the decades,
while the lower end of the lake had no change. This showed that the ground was
doming and that the volcano was alive.
In 1979, Smith published his findings – referring to Yellowstone as "the living, breathing caldera". After a
"swarm" of "mostly tiny" earthquakes in 1985, Smith revised his metaphor to Yellowstone being the "living, breathing, shaking
caldera."
To this day, Smith continues his work at Yellowstone National Park
in efforts to see beneath the park's surface. The continued rise and fall of
the caldera has caused many to question when and if it will erupt. "We call
this a caldera at unrest…the net effect over many cycles is to finally get
enough magma to erupt. And we don't know what those cycles are," said Smith.
Waiting on the Next
Eruption
The lingering, unanswerable question of whether Yellowstone will erupt again and to what scale remains.
Some scientists believe that a modest eruption is likely sometime. Will it be a
super-eruption that will kill-off all of mankind and send the Earth into
volcanic winter for hundreds of thousands of years? These questions cannot be
known at this time.
Now-retired Bob Christiansen believes there is a possibility
that Yellowstone may be safely bottled up. The
hot spot that once formed calderas in the basin and range of the West is now
reportedly lodged under the thick crust of the Rocky
Mountains. ""I think that the system has more or less
equilibrated itself…but that's an interpretation that would
not stand up in court," said Christiansen.
What do you think?
Additional Reading about Yellowstone on CR4:
Yellowstone National Park -
Hot and Steamy (Part 1) Part
2
Yellowstone
National Park Has Its Own Grand Canyon
Resources:
http://ngm.nationalgeographic.com/2009/08/yellowstone/achenbach-text
http://www.jaunted.com/story/2009/7/21/73056/7458/travel/Things+At+Yellowstone+Aren%27t+As+Calm+As+Once+Thought
NatGeo
Photo Gallery of Yellowstone
Thanks to TechoutReach
for bringing this topic to my attention!
| 
Re: Yellowstone: Waiting with Bated Breath
