Cochise College Student Papers in Geology
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Roger Weller, geology instructor
wellerr@cochise.edu
Yellowstone Volcano
by Tyler Leucht
Physical Geology
Spring 2010
Hell On Earth: The Yellowstone Caldera
Most of you might not know that below the peaceful park of Yellowstone lies one of the
largest volcanoes on the planet. It is a resurgent caldera. According to Roger Weller, professor
at Cochise College, this is a form of volcanism in which a collapsed crater is formed after the
explosive eruption of a magma chamber that has uplifted the surface of the earth. The
Yellowstone caldera is also known by a different name. It is a name given to only a select few of
volcanoes around the world. It is referred to as a super volcano.
The USGS defines a super volcano as
being a volcanic center that has had an eruption of
magnitude 8 on the Volcanic Explosivity Index (VEI), meaning the measured deposits for that
eruption is greater than 1,000 cubic kilometers or 240 cubic miles. The magma chamber below
is believed to be about 40 by 80 kilometers across, the top of the chamber is about 8
kilometers deep and the bottom around 16 kilometers deep. This is where the geysers and
seismic activity above get their power.
Not if, but when this volcano erupts it will be a disaster of epic
proportion. The blast
would be one million times more powerful than the bomb dropped on Hiroshima during World
War II, and one thousand times worse than the eruption of Mt. St. Helens. Surrounding areas of
60 miles would be completely obliterated. The entire western United States would be blanketed
by ash and it could reach as far as Washington D.C. No one would be safe within one thousand
miles of the eruption.
Next would come the pyroclastic flows (pyroclastic cloud) released from the eruption.
The pyroclastic flow is basically a high speed avalanche of hot ash, rock fragment, and gas that
moves during explosive eruptions. The flow can reach up to fifteen-hundred degrees Fahrenheit
and move at speeds ranging from one-hundred to one-hundred fifty miles per hour and is capable
of knocking down and burning anything in its path. The flow from this particular eruption could
reach as far as Las Vegas.
To be caught in the flow wouldn’t matter very much because it
wouldn’t last very long.
If, for some reason, breathing the hot gas and volcanic ash didn’t kill you the temperature inside
alone would be enough to boil your skin off. In some cases your brain would explode out of
your skull due to it boiling out of control. Although you could be one of the lucky ones and just
have your body literally blown to pieces after coming into contact with one of these flows.
As amazingly awful as that sounds it isn’t even the worst part. When it finally blows, the
amount of volcanic ash and sulfur dioxide released into upper atmosphere could prove to be
catastrophic. The gases released would create a thin cloud like sheet around the planet blocking
the sun’s rays for up to approximately six years and would create a mini ice age. Temperatures
would drop globally anywhere from ten to twenty degrees. Snow in June and frost in August
would easily kill off the “bread basket of North America” as well as the “bread basket of
Europe.” No crops being grown would easily lead to the starvation of millions and potentially
billions. Farm animals would die due to breathing in the ash being circulated. This event could
easily wipe out sixty percent of the species that occupy the planet today.
The last super volcano to blow was Lake Toba seventy-four thousand
years ago. The
amount of material released by this super volcanic eruption was several thousand times more
than Mt. St. Helens. The eruption nearly wiped out the human race and there were only an
estimated five-thousand survivors. We are all descendants from this remaining
population.
The Yellowstone Caldera is very dangerous. It can kill in many
different ways. Ash
deposits, pyroclastic flows, aerial bombs shot by volcano, lava, a mini ice age and there is no
way to stop it. Man survived it once and we are all the descendants of those survivors so
surviving is in our blood. The Yellowstone Caldera erupts about every six-hundred thousand
years. Its last eruption was six-hundred forty thousand years ago. It’s due for another eruption,
but I ask, can man survive another eruption?
http://skywalker.cochise.edu/wellerr/aawellerweb.htm
www.yellowstonenationalpark.com