Montana News

Jan 29, 2010 11:27 AM

Yellowstone earthquake swarm nears 1,500

Almost 1,500 earthquakes have been recorded in Yellowstone National Park during a recent swarm over the last two weeks.

Since January 17 when the swarm began, there have been 1,497 earthquakes with magnitude 0.4 to 3.8 recorded on the west side of the park through 9 a.m. Thursday, January 28, the park said in a news release.

Over the last couple days, a pair of earthquakes of magnitude 3.1 and 3.2 occurred in the park, according to the University of Utah Seismograph Stations. The magnitude 3.1 event occurred at 12:52 p.m. on Wednesday, January 27.

The magnitude 3.2 occurred at 1:46 a.m. January 28. Both shocks happened about nine miles to the southeast of West Yellowstone and about 10 miles to the northwest of Old Faithful. Both quakes were reported felt in the park.

The largest earthquake in the swarm as of 9 a.m. January 28 was a magnitude 3.8. Of the 1,497 located earthquakes, 12 events were of magnitude larger than 3, 111 events were of magnitude 2 to 3, and 1,374 events were 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, according to the park.

Earthquake swarms are relatively common in Yellowstone, the park said.

"Yellowstone Volcano Observatory scientists still consider that the swarm events are likely the result of slip on pre-existing faults and are not thought to be caused by underground movement of magma. Currently there is no indication of premonitory volcanic or hydrothermal activity, but ongoing observations and analyses will continue to evaluate these different sources," the park said in the news release.

Click here for felt reports. Seismic information on the earthquake can be viewed at the University of Utah Seismograph Stations.

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