Earthquake swarm in Yellowstone

A map showing recent earthquake activity in the vicinity of West Yellowstone as of the morning of June 20, 2017. The orange line in the bottom right marks the edge of the park's caldera. 

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The earthquake swarm affecting the western edge of Yellowstone National Park has included more than 460 quakes so far, scientists say.

The University of Utah, whose seismography stations monitor the park’s quake activity, said Monday night that 464 quakes have been recorded since June 12, including a magnitude 4.4 earthquake near West Yellowstone on June 15, which was the largest of the swarm to date.

In addition, the swarm has consisted of five quakes in the magnitude 3 range, 57 quakes in the magnitude 2 range, 238 in the magnitude 1 range, 157 in the magnitude zero range and six weaker quakes. The quakes have ranged in depth from zero to 9 miles, relative to sea level.

In total, 115 people reported to the U.S. Geological Survey that they felt the June 15 earthquake near West Yellowstone.

In its report, the University of Utah noted that earthquake swarms are common in Yellowstone and make up about half the total seismic activity of the region.

According to the National Park Service, the largest swarm happened in 1985, when more than 3,000 quakes were recorded in a three-month period in the northwestern portion of the park.

The park is one of the most seismically active areas in the U.S., experiencing 1,000 to 3,000 earthquakes a year. The quake activity is caused by the large number of faults in the park associated with the volcano that underlies Yellowstone.

If you think you felt an earthquake, you can fill out a “felt” report at: http://earthquake.usgs.gov/earthquakes/dyfi/.

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