More than 100 aftershocks have rattled southeastern Idaho since a 5.3 magnitude quake hit near the town of Soda Springs late last week, and experts say they could continue for another week or so. The 5.3 quake hit about 6pm Saturday, the AP reports. There were no reports of injuries or damage, though officials say 17,000 people reported feeling the 5.3 quake from as far away as Salt Lake City. By noon on Tuesday, more than 102 additional earthquakes had been recorded in the region by the US Geological Survey, all at magnitudes of 4.5 or less. They'll likely taper off by the end of next week, says John Bellini, a USGS geophysicist. "They can go on for days or weeks, and they'll get smaller in size and frequency."
Lee Liberty, a Boise State University geosciences professor, says Idaho experiences earthquakes of a magnitude 5 or above on average about every five years, based on news reports and other records dating back to 1872. They don't happen like clockwork, however, he notes. "This is the largest event since 1983," Liberty says, referring to Idaho's biggest recorded quake, a 6.9 temblor. "So it has been a generation, but historically we expect them more frequently than we've been seeing them." Two schoolchildren were killed in that quake when a brick storefront collapsed. Aftershocks in that event continued for more than a year—one reaching a magnitude of 5.8—and the mountains and neighboring valley shifted nearly 14 feet apart in some places. (Read more earthquake stories.)