Posted April 23rd, 2015 at 6:00 pm (UTC-4)
Yellowstone National Park’s Grand Prismatic hot spring are among the park’s many hydrothermal features. (Robert B. Smith & Lee J. Siegel)
Yellowstone National Park’s many geothermal features, including its estimated 10,000 hot springs and geysers, draw millions of visitors each year.
There’s good reason why the approximately 8,983 square km park has such a high level of geothermal activity. You see, the park sits atop one of the world’s largest active volcanic systems.
According to the US Geological Survey, Yellowstone’s supervolcano exploded with three cataclysmic volcanic eruptions over the past 2.1 million years. The most recent took place about 640,000 years ago.
Scientists say those three catastrophic Yellowstone supervolcano eruptions covered much of North America in volcanic ash. A similar eruption today would be equally devastating, according to researchers.
Today, a number of people – possibly inspired by a few conspiracy theories and docudrama television programs – are concerned that a significant and catastrophic eruption of Yellowstone’s supervolcano is imminent.
And seismologists from the University of Utah have made a new discovery that may add to these concerns.
This cross-section illustration – cutting southwest-northeast under Yelowstone – depicts the supervolcano’s “plumbing system” as revealed by recent seismic imaging. (Hsin-Hua Huang, University of Utah)
The scientists said they discovered and made images of a reservoir of hot and partially molten rock located about 19 to 45 km below the Yellowstone supervolcano. The researchers added that this reservoir is about 4.4 times larger than the long-known and shallower magma chamber above.
According to Jamie Farrell, a co-author of a study published in the journal Science, the reservoir of hot rock would fill the 4,168 cubic kilometer Grand Canyon 11.2 times. The magma chamber above it was calculated to fill the Grand Canyon 2.5 times.
“For the first time, we have imaged the continuous volcanic plumbing system under Yellowstone,” said the study’s first author Hsin-Hua Huang, a postdoctoral researcher in geology and geophysics, in a press release.
“That includes the upper crustal magma chamber we have seen previously plus a lower crustal magma reservoir that has never been imaged before and that connects the upper chamber to the Yellowstone hotspot plume below,” he added.
To allay any fears that the Yellowstone volcano is about to blow up, the seismologists emphasized that its “plumbing system” is neither larger nor is it any closer to erupting than before.
Robert Smith, a research and emeritus professor of geology and geophysics at the University of Utah, took this a step further, saying the annual chance of the supervolcano erupting is 1 in 700,000.
One of the most popular hydrothermal features at Yellowstone park is the geyser Old Faithful, shown here during one of its regular eruptions. (Jon Sullivan/Wikimedia Commons)
The researchers also stressed that contrary to what many people may think, the magma chamber beneath the Yellowstone supervolcano and the magma reservoir beneath that are not bubbling with molten rock. While the rock material is hot, the researchers said it’s mostly solid and spongy, with only pockets of molten rock within it.
The hot rock in the upper magma chamber contains an average of about nine percent molten rock, according to researchers’ calculations. That is pretty much in line with past estimates of between 5-15 percent of molten rock in that chamber. The researchers also found that the contents in the lower magma reservoir are made of about two percent of melted rock.
Study co-author Fan-Chi Lin, assistant professor of geology and geophysics, said that the new research is providing a “better understanding the Yellowstone magmatic system.”
“We can now use these new models to better estimate the potential seismic and volcanic hazards,” he said.