NORMAL - Like many other Central Illinoisans, Julie Crowe of Normal had two reactions that don't usually go together after Friday morning's 5.2-magnitude earthquake.

"That was pretty cool," she said as she described feeling the quake at her mother's home. That was followed moments later by, "It's very unsettling."

Though the 4:30 a.m. temblor - which was felt across the country and one of the strongest ever recorded in Illinois - was centered about 20 miles southeast of Olney, Central Illinois was well rattled. The quake was enough to wake up people throughout the area, and aftershocks kept talk of fault lines and "Did you feel it?" going all day.

But for the most part the quake stayed an earthshaking water cooler topic, causing no major damage or injuries in Central Illinois, according to reports from area public-safety agencies swamped with calls early Friday by confused residents.

An aftershock around 10:15 a.m. - one of several Friday morning - had a preliminary magnitude of 4.6 on the Richter scale, according to the U.S. Geological Survey. It was felt across Central Illinois. Another aftershock around 10:05 p.m. Friday centered around the same area in Southern Illinois was registered at 2.7, according to the USGS.

The quake - felt in Central Illinois for 10 to 30 seconds, depending on whom you ask - is believed to have involved the Wabash fault, a northern extension of the famed New Madrid fault, about six miles north of Mount Carmel, said USGS geophysicist Randy Baldwin.

State and county transportation officials were out in force early Friday, checking bridges and other structures for damage, but inspectors didn't report any affected roadways, according to the Illinois Department of Transportation.

State Farm Insurance Cos., the largest provider of earthquake coverage in the area, reported only a handful of damage claims by the afternoon, mostly in Southern Illinois. But State Farm spokeswoman Missy Lundberg said that at least one office in the Twin Cities was getting a lot of new calls asking about getting earthquake coverage.

Though the quake happened too early for children or staff to be at schools, area district officials and college administrators said Friday that earthquake drills are practiced and plans for temblors are on the books.

"It was all the attention to the New Madrid fault line. That's when we started adding the earthquake drills," Unit 5 Superintendent Gary Niehaus said.

He was referring to predictions a few years ago of a possible recurrence of the devastating quakes in 1811 and 1812 along the fault that straddles the Mississippi River in southern Missouri. That concern led about seven or eight years ago to a new focus on earthquakes, he said.

At the time he was a superintendent in Salem, about 60 miles west of Friday's quake's epicenter.

At Illinois Wesleyan University in Bloomington, Darcy Greder, associate dean of students, said quakes are in the school's emergency response plans, though after 31 years on the campus, quakes don't top her list of worries.

"If you were at San Francisco State, you'd be running drills all the time, and people would know where to find reinforced doorways," she said. But life on an Illinois campus doesn't bring the same urgency, she said.

Scott Deal of Bloomington said he woke to the shaking of a lampshade at the side of his bed, then felt the 10:15 a.m. aftershock while working at State Farm's south corporate campus.

"I've always wanted to experience an earthquake," Deal said, with the caveat that he doesn't want to go through a violent, destructive one.

Quakes in Central Illinois?

The last earthquake in the region near the New Madrid fault to approach the severity of Friday's temblor was a 5.0-magnitude quake that shook a nearby area in 2002, Baldwin said.

But the chances of an earthquake causing damage in Central Illinois are "pretty slim," said Robert Nelson, a geology professor at Illinois State University, Normal, who used his Friday morning lecture to discuss the quake with his students.

Central Illinois has some distance from Southern Illinois fault lines and rests on glacial till, a mix of material deposited by glaciers that dampens earthquake waves, he said.

Nelson said an earthquake like Friday's is expected about once every five or seven years.

A magnitude 6.0 quake, in contrast, is when damage becomes a larger concern.

"Each time you're increasing the magnitude, you're increasing the earthquake energy by about 32 times," Nelson said. "We were quite a ways away from a damaging earthquake."

Still, it shook skyscrapers in downtown Chicago and was felt by Deal's sons near Indianapolis, and in Louisville, Ky., and St. Louis.

Closer to the epicenter, bricks shook loose, walls cracked and a porch collapsed.

The quake was felt across such a large area because of the solid bedrock underneath the Midwest, Nelson said. In Southern California, for example, a 5.2-magnitude earthquake would only be felt about 40 to 50 miles away because the ground is more broken up, Nelson said.

"Once the energy is out there (in the Midwest), there is virtually nothing to slow those waves down," Nelson said.

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Shaken and stirred

Here are some quick facts about earthquakes and when they've caused trouble in Illinois.

Playing the odds

• The U.S. Geological Survey says 796 earthquakes have occurred in the U.S. to date in 2008.

• Illinois experiences one earthquake a year on average. Only one quake in 20 years causes damage.

• Scientists estimate the likelihood of a damaging quake measuring 6.3 or greater on the Richter Scale in the Midwest in the next 15 years at 40 percent to 63 percent. The likelihood is nearly 100 percent one will occur in the next 50 years.

• Serious damage occurs from a quake only once in every 70 to 90 years in the state.

• The Illinois Geological Survey says devastating earthquakes in the central U.S. occur only once in every 700 to 1,200 years.

Past quakes

• The New Madrid Seismic Zone, which reaches into Illinois, experienced three huge quakes estimated at more than 8.0 on the Richter Scale during the winter of 1811-12. The region was sparsely populated, so only a few injuries are known. But, the force appeared to reverse the course of the Mississippi River for a time and rang church bells in Boston. The power opened fissures, formed lakes, uprooted and snapped trees, sank or raised large sections of land more than 20 feet and affected 600,000 square miles.

• USGS scientists think a major quake occurs on the New Madrid fault about once every 500 years.

• The last reported damage-causing earthquake in Illinois measured 5.0 and centered in southeastern Illinois near Lawrenceville and Olney in June 1987.

• The last major quake in the Midwest happened Halloween 1895 and was centered just south of Charleston. The magnitude was estimated at 6.8, and people as far away as Pennsylvania reported feeling the tremor. Sill, no one was killed or injured, and no buildings collapsed.

Safety tips

• Strap water heater securely to wall.

• Some walls may require additional bracing; check with construction experts.

• Use flexible connectors for natural-gas lines to appliances.

• Learn how to shut off all utilities.

• Have fire extinguishers strategically located on each floor.

• Make sure the chimney and roof are in good condition and well-supported.

• Make sure mirrors, picture frames, hanging plants and lamps are mounted securely.

• Keep beds away from glass or any hanging object.

• Brace tall furniture, bookcases and refrigerators and attach to walls.

• Use sturdy latches on cabinet doors.

• Be sure your house is bolted to the foundation.

• Establish an emergency meeting place should your family get separated.

SOURCES: U.S. Geological Survey and Illinois State Geological Survey; tips from State Farm Insurance Cos.

Michele Steinbacher and The Associated Press contributed to this report.