Some facts about Friday's earthquake:

— The 5.2-magnitude temblor occurred at 5:37 a.m. EDT and was centered six miles southwest of West Salem, Ill., and 45 miles west of Evansville, Ind.

— It was felt as far away as Atlanta and Michigan.

— The temblor was one of the strongest ever recorded in Illinois. The strongest was in 1968, when a 5.3-magnitude temblor was centered near Dale in Hamilton County, about 75 miles southeast of St. Louis.

Biggest quakes by state

The U.S. Geological Survey says Friday's earthquake was generated by a northern branch of the New Madrid fault zone, the most seismically active in the country east of the Rockies. It produced a series of powerful quakes in 1811 and 1812 that were estimated at magnitude 7.0 or greater.

The most powerful New Madrid quakes since then for each state in the area:

Arkansas: 1843, magnitude 6.3 in northeast Arkansas that caused widespread damage but no serious injuries or deaths.

Illinois: 1968, a magnitude 5.3 quake in southern Illinois that led to scattered damage but neither serious injuries nor deaths.

Indiana: 1909, a 5.1 quake near Terre Haute that caused only minor damage.

Kentucky: 1980, a magnitude 5.2 quake near Maysville, about 100 miles northeast of Louisville, that was widely felt but caused only minor damage.

Missouri: 1895, magnitude 6.6 near Charleston in southeast Missouri; widespread property damage but no deaths reported.

Tennessee: 1865, a 5.0 near Memphis that caused only scattered damage.

Source: U.S. Geological Survey