WEST SALEM, Ill. – A 5.2-magnitude earthquake centered in southern Illinois rattled homes and skyscrapers across the Midwest early Friday, causing little damage but surprising residents unaccustomed to such a powerful temblor.

“I would have never thought it was an earthquake because I’ve never felt an earthquake before,” John Xydis, freshman in Aviation, said.

The quake _ one of the strongest ever recorded in Illinois _ occurred just before 4:37 a.m. and was centered six miles southeast of West Salem, Ill., and 45 miles west of Evansville, Ind.

Some students at the University slept through the quake without knowing what happened until Friday morning, while others were confused about what was occurring.

“I felt my bed rocking, and at first I thought someone was shaking my bed. I woke up, and there wasn’t anyone there so I thought I was tweaking,” Cory Travis, sophomore in LAS, said.

Initially pegged as a 5.4 earthquake, the U.S. Geological Survey revised its estimate to give it a value of 5.2. Two aftershocks during the next three hours measured 2.6 and a 2.5, the agency reported.

Dr. Amr Elnashai, director of the Midamerica Earthquake Center, said aftershocks will continue in the area for the next two to three days, but they will become significantly weaker each day, dropping at least one full magnitude level each day.

The strongest earthquake recorded in Illinois was in 1968, a 5.3-magnitude temblor centered near Dale in Hamilton County, about 75 miles southeast of St. Louis, according to the USGS. Minor damage was widespread, but there were no serious injuries or fatalities.

West Salem is in Edwards County, and dispatcher Lucas Griswold said the sheriff’s department received several calls about the earthquake but only reports of minor damage and no injuries.

“Oh, yeah, I felt it. It was interesting,” Griswold said. “A lot of shaking.”

In Mount Carmel, 15 miles southeast of the epicenter, a collapsed porch trapped a woman in her home, but she was quickly freed and wasn’t hurt, said Mickie Smith, a dispatcher at the police department. The department took numerous other calls, though none reported anything more serious than objects knocked off walls and shelves, she said.

Also in Mount Carmel, a two-story apartment building was evacuated because of loose and falling bricks. Police cordoned off the building, a 1904 school converted to residences.

U.S. Geological Survey scientists in Denver were examining data about the quake, said geophysicist Carrieann Bedwell.

“This was widely felt, all the way to Atlanta, a little bit in Michigan,” she said.

Residents in Milwaukee, Cincinnati, Louisville and St. Louis also reported feeling the earth shake. In Louisville, the quake caused bricks to fall off part of a building near downtown, and television video showed bricks strewn in the street, but the mayor’s office said there were no reports of injuries.

“It shook our house where it woke me up,” said David Behm of Philo, 10 miles south of Champaign. “Windows were rattling, and you could hear it. The house was shaking inches. For people in central Illinois, this is a big deal. It’s not like California.”

Though Champaign experienced the earthquake, there are currently no reports of damage to any buildings or property, said Gary Belman, building safety supervisor for Champaign.

“It’s been a good conversation piece, but that’s about it,” Belman said.

Roland White, city engineer for Champaign, said the roads and bridges in the area have been inspected by the Illinois Department of Transportation and they are safe. No action has been taken so far.

“All structures have limits, but this earthquake was not powerful enough,” White said.

Phones started ringing at the Crawford County Sheriff’s Department in Robinson, about 15 miles north of the epicenter, but there were no immediate reports of damage, dispatcher Marsha Craven said.

“They didn’t know if it was the refinery blowing up or an earthquake,” she said, referring to the a local petroleum refinery.

In Cincinnati, one woman said she felt something that lasted for up to 20 seconds.

“All of a sudden, I was awakened by this rumbling shaking,” said Irvetta McMurtry, 43. “My bed is an older wood frame bed, so the bed started to creak and shake, and it was almost like somebody was taking my mattress and moving it back and forth.”

The quake shook skyscrapers in Chicago’s Loop, 230 miles north of the epicenter, and in downtown Indianapolis, about 160 miles northeast of the epicenter.

The Illinois State Police sent troopers to the Edens Expressway where rebar pushed up from the pavement Friday morning and “flattened a few tires,” said spokesman Lt. Scott Compton.

The earthquake spread out from a five to six mile area in West Salem before spreading throughout the country. According to Elnashai, the large radius of affected people is because of the solid layer of bed rock underneath the Midwest. Unlike the porous earth underneath the West coast, the solidarity of the Midwest allows the vibrations to continue carrying.

It was uncertain whether the quake had caused the expressway damage, Compton said.

The Midwest, most notably southeast Missouri and southwest Illinois, is home to the New Madrid fault, a network of deep cracks in the earth’s surface.

The fault, at the center of the country’s most active seismic zone east of the Rockies, produces numerous small quakes a year, most too weak to be noticed by the public.

But in 1811 and 1812, it produced a series of earthquakes estimated at magnitude 7.0 or greater.

Elnashai said this earthquake occurred in the Wabash Valley area. In this area, an earthquake of this magnitude is about as strong as one would get, as it normally would max out at around 5, he said. Also, earthquakes in the Wabash Valley area tend to happen every 10 to 20 years, and are often not noticed by the public.

Even before Friday, earthquakes _ or the possibility of them _ in the central U.S. were getting plenty of attention.

Early next month, agriculture extension officials from various regional states already are scheduled to convene an earthquake summit, hosted by the University of Illinois’ extension service.

Planners of the New Madrid Earthquake Emergency Preparedness Conference in the Ohio River community of Metropolis, Ill. say representatives from Illinois, Arkansas, Indiana, Missouri and Tennessee are to attend.

Michael Logli, Paolo Cisneros and Pamela Nisivaco contributed to this report.