YELLOWSTONE NATIONAL PARK, Wyo. -- The U.S. Geological Survey says the magnitude-4.8 earthquake that shook northern Yellowstone National Park is the strongest there since 1980.
But the Sunday quake was still considered relatively light, and its location didn't raise concerns about the park's supervolcano, which experts say has the potential to erupt with a force about 2,000 times the size of Mount St. Helens and would have worldwide effects.
The University of Utah Seismograph Stations says the earthquake occurred at 6:34 a.m. about 4 miles north-northeast of the Norris Geyser Basin. It was felt in the Montana border towns of West Yellowstone and Gardiner.
About an hour before the Yellowstone quake, a magnitude-3.1 quake hit about 9 miles northwest of Challis, Idaho.
There were no immediate reports of damage or injuries in either earthquake.
Yellowstone sees frequent earthquakes. Since Thursday, there have been at least 25 recorded.