Thursday - March 02, 2006

Where Ya Gonna Go When The Volcano Blows?

Trivia Question: Where is the largest active volcano in the world located?

Non-Trivial Answer: Yellowstone National Park in Wyoming.

The article below states that the last eruption of this SUPER-VOLCANO (25 miles in diameter) was 640,000 years ago. Can you guess how often this monster blows its top, based on geological surveys and scientific data? If you guessed “every 600,000 years” then you would be right. If you also guessed that everything East of Yellowstone, all the way to Illinois would be covered in several feet of ash and volcanic debris you would be right on the money. If you further extrapolated the nature of this phenomenon, you will have guessed by now that the cloud of ash would cover the planet and we would face a 3-4 year long hard, cold winter everywhere. So much for glowball warming ....

Yellowstone Bulge May Cause Thermal Unrest
March 2, 2006, 11:59 AM EST

BILLINGS, Mont. (AP)

A newly discovered surface bulge in Yellowstone National Park may be responsible for some unexpected geothermal activity in recent years, according to a study by U.S. Geological Survey scientists.

The bulge, about 25 miles across, rose 5 inches from 1997 to 2003 and may have triggered some thermal unrest at Norris Geyser Basin, including a sudden rise in temperatures, new steam vents and the awakening of Steamboat geyser.

The findings are part of a paper set to be published Thursday in the journal Nature. Charles Wicks, one of the USGS scientists who worked on the study, said much of what happens beneath the park’s surface remains a mystery, but more is being learned about the Yellowstone caldera, the huge bowl-shaped collapsed volcano in the middle of the park that last erupted 640,000 years ago.

Geologists discovered the dome on the northern rim of the caldera several years ago, and Wicks and others used satellite images and other tools to track its swelling. Wicks and his colleagues theorize that molten rock moved out of the caldera and beneath the area of the inflating dome, which has been named the North Rim Uplift Anomaly. The floor of the caldera sank as the molten rock left.

Around the same time, some unusual activity began occurring in and around Norris Geyser Basin, according to the USGS findings. Steamboat geyser erupted in May 2000 after nine years of dormancy, and then erupted five more times between 2002 and 2003. The nearby Porkchop geyser also sprang to life after 14 years of dormancy. Ground temperatures at Norris, the hottest and most unstable geyser area in the park, rose so high in 2003 that Yellowstone officials closed some boardwalks out of fear that visitors might be burned.

And just north of Norris near Nymph Lake, a series of steam vents churned and emitted white clouds of gas. Scientists studying the shore of Yellowstone Lake found that the caldera has been rising and falling for at least 15,000 years, sometimes swinging more than 10 feet. Henry Heasler, Yellowstone’s lead geologist, said research about the heaving caldera could play a role in predicting volcanic activity and help ensure the public’s safety. “We’ve known that the caldera breathes,” Heasler said. “Now we’re starting to get a much better idea of those respirations.”

Scientists have revealed that Yellowstone Park has been on a regular eruption cycle of 600,000 years. The last eruption was 640,000 years ago…so the next is overdue. The next eruption could be 2,500 times the size of the 1980 Mount St. Helens eruption. Volcanologists have been tracking the movement of magma under the park and have calculated that in parts of Yellowstone the ground has risen over seventy centimeters this century.

Volcanic activity began in the Yellowstone National Park region a little before about 2 million years ago. Molten rock (magma) rising from deep within the Earth produced three cataclysmic eruptions more powerful than any in the world’s recorded history. The first caldera-forming eruption occurred about 2.1 million years ago. The eruptive blast removed so much magma from its subsurface storage reservoir that the ground above it collapsed into the magma chamber and left a gigantic depression in the ground- a hole larger than the state of Rhode Island. The huge crater, known as a caldera, measured as much as 80 kilometers long, 65 kilometers wide, and hundreds of meters deep, extending from outside of Yellowstone National Park into the central area of the Park.

The most recent caldera-forming eruption about 650,000 years ago produced a caldera 53 x 28 miles (85 x 45 kilometers) across in what is now Yellowstone National Park (Figure 2). During that eruption, ground-hugging flows of hot volcanic ash, pumice, and gases swept across an area of more than 3,000 square miles. When these enormous pyroclastic flows finally stopped, they solidified to form a layer of rock called the Lava Creek Tuff. Its volume was about 240 cubic miles (1,000 cubic kilometers), enough material to cover Wyoming with a layer 13 feet thick or the entire conterminous United States with a layer 5 inches thick. The Lava Creek Tuff has been exposed by erosion at Tuff Cliff, a popular Yellowstone attraction along the lower Gibbon River.

Source: “What’s In Yellowstone’s Future?” - US Geological Survey, 2005 Report

Posted by The Skipper     on 03/02/2006 at 01:47 PM   
Filed Under: • Science-Technology •  
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