The swarm, which began Sunday night, isn’t necessarily unusual. The rest of the world is dealing with higher-than-normal seismic activity — besides the well-documented earthquakes in Haiti, other places like Oklahoma are experiencing rumbles more severe than Yellowstone; a 4.0 earthquake was recorded in Oklahoma Monday, for example.
Here’s the specifics on the swarm, from the University of Utah Seismograph Stations:
The swarm is located about 10 miles northwest of Old Faithful, WY and 9 miles southeast of West Yellowstone, MT. The largest earthquake in the swarm as of 3 PM, January 19, 2010, was a magnitude 3.7 event that occurred at 2:31 PM, MST, January 19, 2010. and there have been 469 located earthquakes in the swarm of magnitudes 0.5 to 3.7. This includes 5 events of magnitude larger than 3, with 34 events of magnitude 2 to 3, and 430 events of magnitude less than 2. There have been multiple personal reports of ground shaking from observations inside Yellowstone National Park and in neighboring communities in Montana and Idaho for some of the larger events. Earthquake swarms of this nature are relatively common in Yellowstone National Park.
At this time the Yellowstone Volcano Observatory does not consider the swarm to be unusual and the earthquakes are likely related to tectonic fault sources. Also there is no indication of premonitory volcanic or hydrothermal activity, but ongoing analyses will evaluate these different sources.
Almost 80 swarms have been recorded in Yellowstone since 1995.