An earthquake rocked Southern Illinois late Tuesday night.  The U.S. Geological Survey recorded a magnitude 2.7 earthquake just before 10:30 last night.  The epicenter was located five miles northwest of Mount Erie or nine miles southeast of Clay City.  The depth measured 17-point-two miles and at this time, no damage has been reported.  In fact, only a couple of reports have been made to the USGS offices.  The light quake was one of 27 earthquakes that was recorded yesterday across the United States.  It was the only earthquake recorded in the Midwest, most of the others were in California or Arkansas.