Expert: Yellowstone earthquake swarms not a precursor to volcanic eruption


Robert “Bob” Smith, the world’s leading expert on the geophysics of Yellowstone National Park, has been searching for the answer to a very important question: “We want to know when things will blow up,” he said.

Smith has spent his life seeking the answer. A distinguished research professor of geophysics and geology and emeritus professor of geophysics at the University of Utah, coordinating scientist of the Yellowstone Volcano Observatory and director for the Yellowstone Seismic Network, Smith has worked in Yellowstone since 1956 and has been a professor of geophysics for 50 years.

While his work through the years has resulted in more than 200 scientific papers and hundreds of presentations at scientific meetings worldwide, it wasn’t until the turn of the century that much of the world started noticing his work.

“Global appreciation for Yellowstone didn’t come about until 2000, when the BBC produced ‘The Super Volcano.’ It brought the world’s attention to Yellowstone,” Smith said.

Smith nonchalantly stated the facts of a Yellowstone super volcano eruption at a recent lecture: An eruption that could last for days, weeks or even years, five to 10 times more powerful than the 1990 Pinatubo eruption in the Philippines that killed 700 — spewing enough material to fill the Grand Canyon twice and a volcanic winter, possibly for years, at temperatures of about 15 degrees Fahrenheit.

Smith gave the sobering news at the Draper Museum of Natural History in the Buffalo Bill Center of the West as part of the Draper After Dark lecture series on July 27.

A recent earthquake swarm — and the press from those on the sensationalizing end of the media — has worried many that the rumbling is a precursor to a volcanic eruption. Since June 12, more than 15,000 earthquakes have been documented. Most are weak, but earthquakes nonetheless, Smith said in front of a large crowd in the Coe Auditorium.

“It’s one of the biggest earthquake swarms we’ve ever had,” he said.

The quakes have continued. On Sunday, a 3.3 magnitude quake was reported by the University of Utah Seismograph Stations. Twenty earthquakes followed by Tuesday night, one registering 2.5 magnitude.

But Smith’s concerns aren’t of the dangers of a super volcano eruption. The chances of that happening are extremely small, he said. However, before the warm comfort of the statement could settle in, he warned of the real natural killer in the region.

“What’s the biggest hazard in Yellowstone? Earthquakes. They’re killers,” Smith said.

On Aug. 17, 1959, a 7.5 magnitude earthquake rocked Hebden Lake, Montana, killing 28 people. It was the last devastating earthquake to hit the greater Yellowstone ecosystem. By that time Smith was already into his third year of work in the nation’s first national park. The scientific work he has accomplished since and the seismic events he has witnessed are too many to list here, but his work continues.

Smith’s team from the University of Utah, in cooperation with the park scientists and facility managers, is currently doing a CAT scan of the earth under the Upper Geyser Basin — including Old Faithful, the park’s largest natural attraction.

“We do CAT scans just like you do when you go to the radiologist; we use the same physics to measure seismic waves,” Smith said.

His research will be published in the coming weeks. Until then the bulk of the information is embargoed. But what they have found, using 133 individual sensors to cover the area from the Firehole River to the infrastructure surrounding the geyser, is that Old Faithful is on the east edge of a large area of highly fractured water- and steam-filled rock that is immediately below the famous lodge and visitors center.

The day after the park closes for the winter, Smith’s crew will resume the CAT scans. But while the information sounds scary, Smith isn’t particularly worried about the findings.

“The things we concentrate on are hazard and risk. They know the systems are there — the area stays clear of snow all winter — and they take precautions,” he said.

Last week, Smith’s team finished installing a new seismographic station at the East Entrance and improved the existing station at the Northeast Entrance. They also installed dozens of GPS and seismic instruments around the park, including five bore holes of varying depths between 50-150 feet, giving them 170 channels of new data.

“Yellowstone now has the most modern volcanic GPS and seismic system in the world,” Smith said.

It’s all in an attempt to answer the questions of the ever changing geology of the Yellowstone caldera. As news of earthquake swarms spreads, more questions come in — even from park officials.

“The question being asked by the rangers at Lake and Mammoth — ‘Are we going to have a big earthquake or volcanic eruption?’ — led us to try to understand how swarms work,” Smith said.

Smith theorizes that when the earthquakes stop, that is the time to start worrying.

“Earthquake swarms are reflecting fluids that are moving out of the magma body, relieving the pressure,” Smith explained in a Sunday phone interview. “If we didn’t have them, they would build up pressure and we’d have eruptions.”