Midwest Earthquake a Wake-Up Call

They said it is also a lesson that earthquakes east of the Mississippi River are felt more widely than those in the west.

The quake was felt as far west as Kansas, as far north as the Upper Michigan, and as far south as Atlanta, Georgia. It shook high-rise buildings in Chicago and homes in Cincinnati and Des Moines. There were no casualties, and little serious damage was reported.

The quake shook some bottles off the shelves in this Chicago liquor store. (Photo credit unknown)

"Earthquakes of comparable size are felt over greater distances in the East than those occurring in the West," said Harley Benz, seismologist for the USGS. "Earthquakes in the central U.S. are infrequent, but not unexpected."

The preliminary magnitude 5.2 earthquake occurred at 4:37 am Central Daylight Time and was centered about 38 miles north-northwest of Evansville, Indiana or 128 miles east of St. Louis, Missouri. It occurred in an area known seismically as the Wabash Valley Seismic Zone.

Today's event is the strongest earthquake in southern Illinois since November 1968, when a 5.4 earthquake occurred.

On Monday, the USGS will be issuing updated earthquake hazard assessment maps for the entire United States. The information on these maps is used to update building codes.

Classified as "moderate," today's event caused some damage and was followed by aftershocks, the largest a magnitude 4.6 that occurred at 10:15 am Central Daylight Time.

Of much greater concern, said Benz, is the potential for the adjacent New Madrid seismic zone to generate severe earthquakes. During the winter of 1811-1812, a series of three very large earthquakes - the strongest earthquakes to strike the lower 48 states during historic times - devastated the area and were felt throughout most of the nation.

Occurring only a few weeks apart on December 16, January 13, and February 7, they generated hundreds of aftershocks, some severely damaging by themselves, which continued for years.

Building codes used in the region incorporate a significant degree of risk from earthquakes, but many buildings constructed before these codes were in place or updated have not been adequately retrofitted, Benz said.

USGS research into ground shaking is used by building officials to update building codes based on the most up-to-date information. As new buildings replace older, more dangerous structures, death tolls from earthquakes have been significantly reduced in the U.S.

Did you feel this earthquake? You can report your experiences here.

More information on this event and the history of the region is found here.

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