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USGS says 260 earthquakes have struck eastern Idaho since Sept. 2


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Courtesy USGS

SODA SPRINGS — The U.S. Geological Survey reports the earthquake swarm that’s been shaking southeast Idaho since Sept. 2 is measuring above previously reported numbers.

As of Sunday evening, the USGS was reporting that there had been 260 quakes during the swarm, including 37 on Sunday.

The USGS’ quake numbers are higher than what’s being reported by the University of Utah Seismograph Stations.

The university reported that 36 quakes occurred on Sunday and 206 since the swarm began on Sept. 2.

All of the quakes reported by USGS and University of Utah are occurring in the Caribou County area to the east, southeast and northeast of Soda Springs. The quakes have been felt throughout southeast Idaho and in Logan, Ogden and Salt Lake City in northern Utah.

Earthquake experts said the USGS and University of Utah use their own networks of seismograph stations to keep track of quakes and that’s why their numbers differ. It’s unclear which set of numbers are more reliable.

The biggest disparity was during the first three days of the swarm — Sept. 2 to 4, when USGS reported that 45 quakes occurred each of those days for a three-day total of 135 quakes compared to the three-day temblor total of 96 from the University of Utah.

USGS reported that there were 23 quakes this past Tuesday, compared to the 20 reported by University of Utah, 29 on Wednesday compared to the university’s 25, and a combined 17 Thursday and Friday compared to the university’s 10.

Both USGS and University of Utah reported the same number of quakes on Saturday — 19.

Earthquake experts said the swarm will likely continue for another week but it could continue for even longer. The swarm doesn’t necessarily mean a larger much more destructive quake could happen in southeast Idaho, but there is a slim chance of such a scenario occurring, earthquake experts say.

Both USGS and University of Utah reported that the most powerful quake in the swarm was a 5.3 magnitude temblor that occurred at 5:56 p.m. on Sept. 2. It’s been years since southeast Idaho has experienced a 5.0 or greater magnitude quake. Such temblors can cause damage to buildings.

Authorities have not reported any damage to structures or injuries to people as a result of any of the recent quakes.

Authorities said that southeast Idaho has never experienced so many quakes in such a short time frame, though the region does experience some seismic activity especially in the Caribou County area.

This story was originally published in the Idaho State Journal. It is used here with permission.