Odyssey

Yellowstone: Supervolcano By Denise Schurr

When you think of Yellowstone National Park, the words "vacation destination" may come to mind. Do you also think supervolcano? Picnickers, hikers, campers, sightseers, and fishermen flock to the park to experience the frequent eruptions of the world-famous Old Faithful geyser, to view the park's 20-mile-long Grand Canyon, and to scout wildlife like buffalo, elk, and moose. But many don't know that Yellowstone is an active volcano that has the power to change the planet's global weather patterns for years to come. Instead of packing for a road trip to the park, should we be packing our rocket ships to Mars? Thermal Feature Hotspot

Over the past two million years, Yellowstone has experienced hundreds of eruptions, including one large eruption and two super eruptions. These formed calderas, or large craters made during a volcanic explosion or collapse of a volcanic cone. The last time the park experienced lava flow was 70,000 years ago, when the Pitchstone Plateau was created. Visitors feel, see, and sniff signs of underground magma. At Yellowstone, there are places where the ground feels warm to the touch and spring waters steam. In these regions, fumaroles--vents in the Earth's surface from which volcanic gas escapes--include a form of sulfur that can make the air smell of rotten eggs.

Paint pots--areas of bubbling mud, named because of their colors--boil and gurgle. Magnificent geysers erupt, shooting water high in the air like a fountain. Yellowstone has more geysers than anywhere else in the world. The heat from the earth's mantle escapes to the crust, creating geothermal activity. The Greek word geo means Earth and therme means heat. 9/21/2015 Along with geothermal activity, there is also seismic activity. Paul Doss, professor of geology at the University of Southern Indiana, says, "There are typically 1,000 to 2,000 earthquakes a year in the park. On some days there may be zero, and on other days there may be a hundred." Most are so small they are not felt by humans.

Super Status What makes a supervolcano--and why is Yellowstone considered one? Jacob Lowenstern, Scientist-in-Charge at the Yellowstone Volcano Observatory, says it's because in the past, "the area has experienced a super eruption."

The U.S. Geological Survey uses the Volcano Explosivity Index to classify eruptions on a scale from 0 to 8. An 8, the highest magnitude, is considered a super eruption. The volume of ash vented from this type of an eruption can be more than 240 cubic miles. This is 1,000 times greater than the eruption at Mount St. Helens in 1980, known as the deadliest and most economically damaging in the United States. Despite its classification as a supervolcano, scientists agree, Yellowstone is not a ticking time bomb. The Yellowstone Caldera is located in the northwest corner of Wyoming. Beneath it is the magma chamber. Doss says this area is 50 miles long by 20 miles wide and 5 miles thick and partially molten. Magma needs to contain about 50 percent liquid or more to erupt, and the whole chamber is 10 to 20 percent molten. The entire thing could not erupt because it is not sufficiently molten. How much warning would we have before a Yellowstone eruption? It's hard to say. With the knowledge scientists have gained from watching other volcanoes erupt and the advancement in technology to monitor changes, there would be warning signs. Numerous large earthquakes, rapid ground deformation, and increasing eruptions in the hydrothermal features such as geysers would be indicators.

Tools and Tech Scientists use special technology to monitor the park, looking for unusual activity. Earthquakes are counted, located, and measured using seismometers, which tell of magma movement. Ground water and hydrothermal water temperatures are taken using digital thermometers. High-resolution GPS units detect elevation changes of the land surface to warn of areas rising or falling at rapid rates. Scientific instruments called gas chromatographs and spectrophotometers read concentrations of volcanic gases in the soil, in the atmosphere, and in hydrothermal water; they are testing for increases or changes. While geologists don't anticipate a super eruption at Yellowstone in our lifetime, a smaller-scale lava flow is possible. Mother Nature is unpredictable, but in this case, under careful watch. The Yellowstone Volcano Observatory website dedicates a page for the public to see the current conditions. Check for yourself, and then go ahead and plan a visit to a supervolcano.

One Hot Theory Large sections on Earth's surface called tectonic plates move over the mantle. John Tuzo Wilson, a Canadian geophysicist and geologist theorized that some groups of volcanoes, like those in Yellowstone, are formed when a tectonic plate moves over a "hotspot." This is a burst of heated rocks or magma rising up from deep inside the Earth. Volcano chains may be formed as plates pass slowly over a hotspot. One example is the Hawaiian Islands--part of an underwater mountain chain composed of more than 80 volcanoes!

Volcano Science The Earth is made up of layers. We live on the thin outer layer, called the crust. Below is the mantle, followed by the molten outer core and finally the solid inner core. Dr. Maya Tolstoy, a marine geophysicist, describes a volcano as anywhere molten rock comes up from the mantle to the surface and erupts. Heated magma, like hot air, wants to rise. Once it reaches the crust, it becomes lava. Volcanoes don't have to be mountains. Wherever lava is leaking through the earth's crust is a volcano. Tolstoy says the majority of the Earth's volcanoes are under the ocean. * * *  Magma - Hot fluid or semifluid rock within the Earth Seismic - Relating to earthquakes Molten - Liquefied by heat Hydrothermal - Warm water, especially water heated by magma Denise Schurr is a freelance writer from Centennial, Colorado. She enjoys sightseeing at national parks with her husband and four children. Citations MLA Schurr, Denise. "Yellowstone: Supervolcano." Odyssey. Jul/Aug 2014: 8-10. SIRS Discoverer. Web. 20 Sep. 2015.