The University of Utah Seismograph Stations reports that a period of increased seismic activity occurred on February 2, 2010 beginning at ~3:30 PM MST. This period of increased activity lasted about 6 hours and included at least 2 events that were reported felt in Yellowstone National Park. The two largest earthquakes during this sequence were magnitude 3.1 and 2.8 that occurred at 7:31 PM and 7:44 PM respectively.
These earthquakes are part of an ongoing swarm in Yellowstone National Park that began January 17, 2010 (1:00 PM MST). The largest earthquake in the swarm as of 7 AM MST, February 03, 2010, has been a magnitude 3.8. There have been 1,719 located earthquakes in the swarm of magnitude 0.3 to 3.8. This includes 14 events of magnitude larger than 3, with 135 events of magnitude 2 to 3, and 1,570 events of magnitude less than 2. There have been multiple personal reports of ground shaking from observers inside the Park and in surrounding areas for some of the larger events
University of Utah.