Southern Illinois was struck Monday by the 18th aftershock to follow a Friday earthquake that was felt across five U.S. states in the Midwest. The 4.5 magnitude aftershock was the second strongest to follow the Friday 5.2 quake. Geologists say the temblor just before 12:40 a.m. registered 4.5 magnitude at its epicenter about 5 miles northwest of Mount Carmel. The location is in the same area as Friday's early morning earthquake, which shook a wide area of the Midwest and caused minor damage. The strongest aftershock to hit the region was a 4.6 magnitude shaker about 5 1/2 hours after the original quake Friday morning.
