Swarm of earthquakes shake Yellowstone National Park

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JACKSON, Wyo. — Until recently, Bob Smith had never witnessed two simultaneous earthquake swarms in his 53 years of monitoring seismic activity in and around the Yellowstone Caldera.

Now, Smith, a University of Utah geophysics professor, has seen three swarms at once.

"It's very remarkable," Smith said. "How does one swarm relate to another? Can one swarm trigger another and vice versa?"

Because concurrent swarms have never been detected in the past, the answers aren't in yet, Smith said. The geophysicist said he "wouldn't doubt" if at least two of the events were related.

Temblors from the three quake swarms mostly hit in three areas: Lewis Lake, the Lower Geyser Basin and the northwest part of Norris Geyser Basin.

The largest earthquake shook the ground near Old Faithful Geyser on Sept. 15.

The epicenter of the magnitude 3.6 quake, the largest in Yellowstone in about a year, was just 6 miles to the north of Old Faithful.

"Generally speaking it needs to be 3.0 or higher for individuals to feel it," Yellowstone National Park spokesman Al Nash told the Jackson Hole News & Guide ( [link to DON'T_USE-THIS] "This one was somewhat stronger than that and it was in an area where a lot of people are."

Yellowstone's recent earthquake swarms started on Sept. 10 and were shaking until about 11:30 a.m. Sept. 16. [link to missoulian.com]