Yellowstone Shaken By Swarm Of Earthquakes
by Travis Larchuk
All Things Considered, January 3, 2009 · A few little earthquakes here or there is just a part of everyday life when you live on top of the largest supervolcano in North America.
But in the past eight days, there have been more than 400 earthquakes at Yellowstone National Park — where the volcanic system powers the geysers, mud pots and steam vents.
Hank Heasler, a National Park Service geologist at Yellowstone, says the constant quakes haven't caused any damage, but they can be a nuisance to rangers who live at the park.
"They have commented to me that they would appreciate it if the earthquakes would stop so they could get a good night's sleep," he says.
When a bunch of earthquakes occur in a concentrated area in a short amount of time, geologists call it a "swarm." They're not unheard of at Yellowstone, but rarely have the earthquakes reached the magnitude and frequency of the past week.
"Back in 1985, there was an earthquake swarm that lasted for three months and had a magnitude 4.7 earthquake associated with it. The current swarm has had a maximum earthquake of only 3.9," Heasler says.
Scientists don't know why this particular swarm is so intense, but Heasler says there's no need to worry about an imminent volcanic eruption. The last time the supervolcano erupted was 640,000 years ago.
"There will be many months of work after the swarm stops to try to figure out the precise cause of these earthquakes," he says