A 4.5-magnitude tremor struck southern Illinois on Monday continuing the series of aftershocks initiated by the 5.2 earthquake which hit the region Friday morning, the U.S. Geological Survey (USGS) informed. This was the 18th earthquake in that series and its epicenter was approximately six miles below ground and about 37 miles (60 km) north-northwest of Evansville, Indiana, or about 131 miles (211 km) east of St. Louis, the USGS revealed.

The inhabitants of southern Illinois felt the tremor at about 12:38 a.m. local time (1:38 a.m. ET).

Local authorities said there were no reports of serious damage or injuries caused by the earthquake.

"Everything just started rumbling and things at my house started shaking. The computer was shaking on top of my desk," said Keith Potter of Santa Claus, Indiana, according to CNN.com.

"The big concern is ... is this just the beginning of the 'big one?'" Potter asked himself rhetorically.

The 18 aftershock earthquakes which followed Friday's tremor haven't measured more than 3.9 on the Richter scale, but the first one was the biggest to hit shake the region called the Illinois basin-Ozark dome in over 40 years.

The first earthquake caused some minor damage across the state. A woman was trapped under a collapsed porch in Mount Carmel according to The Associated Press. Fortunately she wasn't injured and was taken from under the porch quickly.

The quake caused debris to fall on a sidewalk in Louisville, Kentucky, and a cornice fell off a brick building, according to a recorded broadcasted by CNN affiliate WHAS-TV.

The quake was felt even in Chicago (Illinois), where it shook the town's skyscrapers, and also in Des Moines, Iowa's capital, were it rattled the windows of the buildings.