"I thought it was going to collapse and I'd end up in the basement," Fenton said. "It was an exciting wake up call. I hear this big bolt, and my impression for the first second was, it was a thunder bolt or an explosion."

Fenton said the worst damage were small cracks to the foundation of the West Salem Grade School. It wasn't a big deal, though, he said, and school was going on as planned today.

In Mount Carmel, 15 miles southeast of the epicenter, one woman was briefly trapped in her home by a collapsed porch but she was quickly freed without injury, said Mickie Smith, a dispatcher at the police department.

In Philo, a town about 10 miles south of Champaign, David Behm said the quake woke him up.

"For people in central Illinois, this is a big deal. It's not like California," he said.

Most people calling police reported windows rattling and beds shaking. People as far north as Chicago and as far east as Cincinnati reported feeling the quake, which apparently caused some minor damage in the Louisville, Ky., area. Video of some buildings in Louisville showed fallen bricks. One report even said it was felt in as many as seven states, including Wisconsin and Ohio.

Kusky said aftershocks typically decrease in intensity and could come a day or two later.

He said a 5.2 in the Midwest is felt more than if the same quake were to happen in California because of rock and soil conditions here.

"In the Midwest, the rocks tend to be harder so we can feel it more," he said. "It shakes the ground longer. In California, the rocks are more soft and it dissipates more quickly."

If some people felt the earthquake lasted only a few seconds — while other felt it lasted 20 or 30 seconds — Kusky said it's based on the foundation of people's houses. A house whose foundation sits on solid bedrock, he said, probably only felt about 5 seconds of shaking. If a house is on a more porous foundation of clay, people probably felt shaking for about 20 seconds.

J. David Rogers, professor of geological engineering at Missouri University of Science and Technology, said the Wabash Valley Seismic Zone is "definitely capable of spawning 7.0 magnitude earthquakes every 1,000 years. We know there was a large event about 4,600 years ago — a magnitude 7 or above."

There also were large ones in 1891, 1986 and 1987.

"This zone has been crackin' off magnitude 5-plus events, and quite a few historic ones," Rogers said. The Missouri University of Science and Technology is based in Rolla.

One problem is that the federal or state governments haven't pumped money into research in the Wabash Valley zone like they have for the New Madrid quake zone. For example, the New Madrid zone has 13 seismographs.