The U.S. Geological Survey at the University of Memphis said both quakes occurred in virtually the same location, about a mile northwest of Ridgely.
The first happened at 12:07
am, and a second tremor quickly followed at 12:08. The tremors were
measured at preliminary magnitudes of 2.6 and 2.8, respectively.
A third quake was detected Sunday morning in southern Illinois. It happened at around 4:40 am, about 11 miles east of Mount Vernon, Illinois. The tremor was measured at magnitude 2.5.
The USGS says that a magnitude of 2.5 is the threshold of humans being able to detect the ground shaking.
