An early morning earthquake rattled northern Illinois on Wednesday , shaking an area about 50 miles west-northwest of downtown Chicago , the U.S. Geological Survey said . Note : USGS revises magnitude down to 3.8 . NEW : ` ` It was so loud , I thought a plane had gone down , '' he says . NEW : Quake in Illinois was three times as powerful . Epicenter was 100 miles from Chicago and 3 miles underground .
Note : USGS revises magnitude down to 3.8 . NEW : ` ` It was so loud , I thought a plane had gone down , '' he says . NEW : Quake in Illinois was three times as powerful . Epicenter was 100 miles from Chicago and 3 miles underground .