Scientists Not Surprised at Midwest Quake
Southern Illinois a Hotbed of Earthquake Activity, Experts Say
As the nation marveled over a rare magnitude 5.2 earthquake that startled Illinois residents early this morning, earthquake experts weren't all that surprised by the temblor, they told ABCNEWS.com.
The earthquake struck southern Illinois about six miles north of Mount Carmel, at 4:37 a.m., violently shaking people from their beds, swaying Chicago skyscrapers and vibrating the earth as far east as Georgia.
As the morning wore on, at least two significant aftershocks rocked the Midwest.
Astonished messages from Midwesterners flew across sites such as Twitter.com about the aftershocks seconds after they were felt, even before the U.S. Geological Survey reported them, and Verizon customers placed three times more calls than normal between 4 a.m. and 5 a.m.
Scientists say the earthquake likely took place on the Wabash Valley fault system, which is in the southern parts of Illinois and Indiana and is near but not related to the larger and more volatile New Madrid fault, which extends farther south.
http://abcnews.go.com/Technology/Weather/story?id=4682373&page=1 
