At 11:32 this morning a 3.5 magnitude earthquake was reported 38 miles east southeast of West Yellowstone, Mont., in Yellowstone National Park — the latest in a swarm of earthquakes that has hit the area in the past week. The 3.5 tremor was followed this afternoon by a 3.2 magnitude quake at 12:40 and a 3.0 at 1:15. The swarm of tremors is the largest series of back-to-back quakes to hit the area in years, according to scientists. Today's quakes came on the heels of a series of tremors on New Year's Day, including a 3.0 at 6:30 p.m. and a 3.1 at 6:21 p.m. "The December 2008 earthquake sequence is the most intense in this area for some years," said the Yellowstone Volcano Observatory. "No damage has been reported within Yellowstone National park, nor would any be expected from earthquakes of this size." According to the observatory, Yellowstone seismicity increased significantly in December because of what it described as an "energetic earthquake swarm" that began on Dec. 26.

The swarm is occurring beneath the northern part of Yellowstone Lake in Yellowstone National Park. The largest of the quakes, according to the observatory, was a magnitude 3.9 at 10:15 p.m. on Dec. 27. The observatory was created as a partnership of the U.S. Geological Survey, Yellowstone National Park and the University of Utah. It was created to monitor long-term volcanic and earthquake activity in the Yellowstone National Park region. The Yellowstone Plateau, which comprises the Yellowstone National Park, is one of the largest super-volcanoes in the world and has gone through three volcanic cycles spanning two million years that included some of the world's largest know eruptions.

Through 5 p.m. Dec. 31, the swarm had included 12 events of magnitude 3.0 to 3.9 and approximately 20 of 2.5 to 2.9, with a total of 400 quakes large enough to be located. The observatory said similar swarms have occurred in the past without triggering steam explosions or volcanic activity. However, the observatory said there is some potential for explosions and that earthquakes may continue and increase in intensity. The observatory said the National Park Service in Yellowstone is being fully informed of the ongoing seismic activity by the University of Utah and the U.S. Geological Survey. The Wyoming Office of Homeland Security is reviewing Earthquake Response Plans and also monitoring the seismic activity that has been felt by Park Service employees and guests at the park. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world.