Where Yellowstone's supervolcano is likely to erupt
Scientists suspect that Yellowstone is capable of an eruption covering half the U.S. in 3 feet of ash, there are no signs of imminent outbursts.
Fri, Sep 14, 2012 at 12:20 PM
The Yellowstone caldera in 2011. (Photo: ZUMA Press)
The currently dormant supervolcano at Yellowstone may erupt with lava flows in the future, and scientists are working to pinpoint where exactly this might happen.
Their findings may improve eruption forecasting in this vast area of volcanic unrest, the researchers said.
Supervolcanoes are capable of eruptions dwarfing anything ever recorded by humanity, spewing out thousands of times more magma and ash than even the catastrophic Krakatoa eruption of 1883.
The supervolcano that lies beneath Yellowstone National Parkwas responsible for the fourth-largest eruption known to science about 2 million years ago, and its activity continues to fuel the park's famous geysers. The most recent giant eruption in the area, which happened about 640,000 years ago, created the oval-shaped, 40- by 25-mile (64- by 40-kilometer) Yellowstone caldera. [Infographic: The Geology of Yellowstone]
There is evidence that Yellowstone might one day explode with another colossal eruption capable of covering half the United States in 3 feet (1 meter) of ash, although there are no signs of any imminent outbursts, and experts agree the odds the supervolcano will erupt in our lifetimes are vanishingly small.
Still, weaker but nevertheless dramatic eruptions could happen every several hundreds of thousands of years, potentially spewing large volumes of lava, the researchers noted.
To learn more about the future of Yellowstone, the research team analyzed some of the youngest volcanic rocks from the area, known as rhyolites, which are made of silica-rich minerals. The composition, shape and other features of crystals in these rocks could shed light on when and how they were formed, and thus on activity deep below the surface.
Their findings suggest the magma that gave rise to these rocks ascended rapidly from sources about 5 to 6 miles (8 to 10 km) below the surface. The researchers propose any volcanism at Yellowstone will probably resume at these sources, which coincide with three major faults in the area. Two of these were the focus of volcanism 70,000 to 174,000 years ago, and the other is currently the most intense source of unrest in the caldera.
"The point of this was to delineate these zones at Yellowstone that might be subject to a higher probability of future eruptions,"said researcher John Stix, a volcanologist at McGill University.
It remains a very difficult question as to when Yellowstone might erupt in the future, Stix noted.
"An eruption there could happen fairly quickly, geologically speaking," Stix told OurAmazingPlanet. "I would think there would be signs beforehand, but how much time beforehand is really unknown — is it days, weeks, months or years?"
Stix and his colleague Guillaume Girard at the University of Iowa at Iowa City detailed their findings in the September issue of the journal GSA Today.
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