The U.S. Geological Survey (USGS) today will issue updated earthquake hazard assessment maps for the entire U.S. Information on these maps is used to update building codes. The USGS map updates come as a strong aftershock shook southern Illinois early this morning, three days after a magnitude 5.2 quake struck the region. The quake is a reminder of the fact that earthquakes can strike anywhere, not just in California and parts of the west. The USGS noted that the event also highlights that earthquakes east of the Mississippi River are felt more widely than those in the west. Apparently the Illinois quake was felt as far west as Kansas, as far north as Upper Michigan, and as far south as Georgia. It is the strongest quake in southern Illinois since a magnitude 5.4 earthquake occurring in November 1968. Check out further I.I.I. earthquake facts & stats.