A small earthquake was reported at Yellowstone National Park at 5:59 this morning, centered in an area around 15 miles north of the the East Entrance. (See above GYR News Map) Measured at a magnitude of 4.1 on the Richter scale, the earthquake was felt as far north as Billings and as far southeast as Thermopolis, Wyoming. The location of the quake in the eastern part of the park is unusual. The last in this area of about this magnitude was one of 3.5 on July 20, 1992 about four miles northeast of Fishing Bridge.
USGS geophysicist John Bellini was quoted by AP as summarizing the quake as being strong enough to wake people up, but probably not strong enough to cause much damage.
Obviously small earthquakes are common in the Yellowstone National Park ecosystem: the Park, after all, is located on top of a volcanic hot spot, and small rumblings are certainly not unusual.