A 5.7 magnitude earthquake shook Utah's Salt Lake City area Wednesday morning, knocking out power in some areas, officials said.The 5.7 quake was centered about 10 miles west of Salt Lake City, starting at 7:09 a.m. MT, the U.S. Geological Survey said."From what we have been able to determine, it doesn't appear this was major shaking," Utah's Division of Emergency Management posted on Twitter shortly after the earthquake.Still, power has been knocked out in some areas, and aftershocks are likely, the division said. Details about the extent of the outages weren't immediately available.At least six aftershocks had been recorded within 20 minutes of the main quake, according to the USGS.This is the state's most powerful quake since 1992, when a magnitude 5.9 temblor struck the St. George area, the division said.Generally in Utah, earthquakes greater than magnitude 5 happen once every 10 years, and quakes greater than magnitude 6 happen once every 50 years, the USGS said.That statement takes into account instrumentation records dating back to 1962 and historical records dating back to the 1850s, the USGS said.