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The crew

Some of the crew who installed the seismic instruments in 2003 admire the Porkchop Geyser pool. From left are Greg Waite, Bob Smith, Chris Dietel, Hank Heasler and others unidentified.

Three areas in Yellowstone National Park’s caldera seem to have the highest probability for volcanism, according to a recently published study.

The faults are near the western rim of the caldera south of West Yellowstone, one in the central region extending south from Norris to about Grant Village, and the third near the northeastern edge of the ancient volcano’s rim extending from about Canyon Village south past Lake.

The information was collected in a study done by Guillaume Girard and John Stix. They both worked at the Department of Earth and Planetary Sciences at McGill University in Montreal at the time, but Girard has since relocated to the University of Iowa.

“Those guys have done a good job,” said Bob Smith, a University of Utah researcher who has long studied the geodynamics of Yellowstone.

Smith said he couldn’t comment on their geochemistry, since he’s not a volcanologist, but Girard and Stix came to the same conclusions that Smith has about the northwest-trending faults that are zones of weakness in the caldera.

The scientists based their predictions on studies they made of two of Yellowstone’s youngest magma flows — the western and central faults — as well as the region in the northeast that has seen “notable geophysical unrest.”

“It's a nice synthesis of what we know about Yellowstone's volcanic history and prospects for future activity,” said Jacob Lowenstern, scientist-in-charge of the Yellowstone Volcano Observatory, in an email. “Most is based on previous work by others, but the article puts it together in an easy-to-read format.”

Molten rock lies very near the surface in Yellowstone, only a few miles underground. All of that heat is what powers the park’s many geothermal features, including mudpots, fumeroles and geysers like Old Faithful.

With magma so close to the surface, Yellowstone’s volcano has erupted many times, leaving a trail of giant craters between present-day Nevada and Wyoming as the surface of the earth moved southwest across the hot spot. The last large eruption, the third in a series at Yellowstone, was about 640,000 years ago and created the park’s massive caldera, or crater. About 150,000 years ago, a smaller eruption created a caldera located at the West Thumb of Yellowstone Lake.

Although no scientists are predicting any massive eruptions of the Yellowstone volcano anytime soon, if the magma reservoir were to become active Stix and Girard said in their paper that the “eruptions would most likely be focused along the two fault lines” to the west. The third parallel fault line in the northeast, “while not hosting volcanism in the last half million years, focuses the most intense caldera unrest and is underlain by the magma reservoir,” they write in their research.

These days any activity of the volcano is picked up by the extensive monitoring network that the Yellowstone Volcano Observatory has set up across the caldera.

“We’ve probably got one of the most modern monitoring networks in the world, and it covers the entire Yellowstone Plateau,” Smith said. “So we’re recording an enormous amount of data.”

Any intrusion of magma into the upper crust in Yellowstone as a precursor to a volcanic eruption would likely trigger seismic activity days, weeks or months before any eruption, Smith added.

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Montana Untamed Editor

Montana Untamed editor for the Billings Gazette.