Yellowstone is situated on a giant, geologically active feature known as a supervolcano and boasts some 75 per cent of the world’s geysers.
More than 250 tremors have been recorded since December 26th, including nine greater than magnitude 3.0 on the Richter scale, according to the University of Utah. The largest, a magnitude 3.9, struck on Saturday and the area was shaken by a 3.3 tremor just after midday on Monday.
While earthquakes are common in the giant park, which covers parts of Wyoming, Idaho and Montana and experiences about 1,000 to 2,000 tremors a year, the intense burst of seismic activity lasting several days has been described as unusual.
“They’re certainly not normal,” said Robert Smith, a professor of geophysics at the University of Utah. “We haven’t had earthquakes of this energy or extent in many years.”
Mr Smith, director of the Yellowstone Seismic Network, which operates seismic stations around the park, said the earthquakes have ranged in strength from barely detectable to Saturday’s 3.9. A magnitude 4 earthquake is capable of producing moderate damage.
“This is an active volcanic and tectonic area, and these are the kinds of things we have to pay attention to,” he said. “We might be seeing something precursory.
“Could it develop into a bigger fault or something related to hydrothermal activity? We don’t know. That’s what we’re there to do, to monitor it for public safety.”
So far, all the quakes have been centred beneath the northwest end of Yellowstone Lake. No damage has been reported and a park spokeswoman said there did not appear to be cause for alarm.
Yellowstone is situated on a giant, geologically active feature known as a supervolcano and boasts some 75 per cent of the world’s geysers. Much of the park sits in a caldera, or crater, which was formed when the massive volcano erupted 70,000 years ago.
Last year a report in the journal Science found the park’s central region was rising up at a rate of up to 7cm a year due to the movement of a pool of magma several miles below the surface.
Mr Smith said it was difficult to say what might be causing the current tremors. He added that the park’s famous geysers and hot springs were a reminder of the magma underground.
“That’s just the surface manifestation of the enormous amount of heat that’s being released through the system,” he said.
In 1959, a magnitude 7.5 earthquake near Hebgen Lake just west of Yellowstone National Park triggered a landslide that killed 28 people. AP