A total of 130 earthquakes shook Yellowstone National Park between Sept. 10 and Sept. 15, according to a University of Utah
press release, though most were too small for a person to feel.
Bob Smith is a geophysicist who has spent the last
53 years monitoring seismic activity in and around the Yellowstone Caldera. During this time, he
told The Associated Press,
he only recently witnessed two simultaneous earthquake swarms, or groupings. Then,
last week, he detected three.
"It's very remarkable," Smith said. "How does one swarm relate to another? Can one swarm trigger another and vice versa?"
The answers aren't clear, though Smith said he "wouldn't doubt" if at least two of the swarms were related.
According to the University of Utah Seismograph Stations, the sequence of swarms began on Sept. 10 and have concentrated around Lewis Lake, the Lower Geyser Basin and northwest of Norris Geyser Basin.
"Notably much of the seismicity in Yellowstone occurs as swarms," the press statement notes.
"
This is pretty unusual, to be honest," Smith said, explaining that an earthquake generally isn't felt until it reaches a magnitude of 3.0 on the Richter scale. The range for the latest swarms have fallen between 0.6 and 3.6.
