Caldera Super Volcano
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What is the Yellowstone Caldera?
Yellowstone Caldera, also known as the Yellowstone
supervolcano, is a highly
geologically active region in Yellowstone
National Park. It measures 55 kilometers by 72 kilometers.
Map of caldera
showing recent major earthquakes
activity is currently exhibited only via numerous
geothermal vents scattered throughout the region, including the famous
Old Faithful Geyser, but within the past two million years it has
undergone three extremely large explosive eruptions. The most recent
such eruption occurred 640,000 years ago, and spread a layer of
volcanic ash over most of the North American continent. Smaller
explosive eruptions, similar to the 1980 Mount St. Helens eruption,
occur every 20,000 years or so; an explosion 13,000 years ago left a 5
kilometer diameter crater at Mary Bay, on the edge of Yellowstone Lake
(located in the center of the caldera). As a result of all this
activity small earthquakes are common; in 2002 about 2,300 earthquakes
were recorded in Yellowstone park. Most of these were too small to be
felt by humans.
as well as the continuing geothermal activity, are a
result of a large chamber of magma located below the caldera's surface.
The magma in this chamber contains gases that are kept dissolved only
by the immense pressure that the magma is under. If the pressure is
released to a sufficient degree by some geological shift, then some of
the gases bubble out and cause the magma to expand. This can cause a
runaway reaction. If the expansion results in further relief of
pressure, for example by blowing crust material off of the top of the
chamber, the result is a very large gas explosion.
A full-scale eruption of the
Yellowstone supervolcano could
result in millions
of deaths locally and catastrophic climactic effects globally.
Fortunately there is little indication that such an eruption is
imminent in the near future, although study of Yellowstone is ongoing
and the system is not yet completely understood. Geologists are closely
monitoring the rise and fall of the Yellowstone Plateau, which averages
1.5 cm per year, as an indication of changes in magma chamber pressure.
proposals are suggested for ways to safely relieve the
buildup of dissolved gas in the Yellowstone magma chamber, usually
involving drilling holes or using explosives to release small amounts
of pressure in a controlled manner. However, none of these ideas are
likely to have a noticeable impact. The magma beneath Yellowstone is
not very mobile so release of dissolved gases from any given point is
not going to do much to the chamber as a whole, and in any event the
scale of the problem is far too large for current engineering
capabilities to handle.
Yellowstone is riding on one of the planet's few dozen hot
spots, where light hot molten mantle rock rises towards the surface.
Hawaii and Iceland lie over similar hot spots.
hot spot has a long history. Over the past 17 million
years or so successive eruptions have flooded lava over wide stretches
of Washington, Oregon, California, Nevada, and Idaho, forming a string
of comparatively flat calderas linked like beads, as the North American
plate moves across the stationary hot spot. The calderas' apparent
motion to the east-northeast forms the Snake River Plain. However, what
is actually happening is the result of the west-southwest motion of the
North American plate with respect to the stationary hot spot deep