Aftershocks from Friday’s earthquake continue to shake Illinois and its surrounding states.

A number of aftershocks have been reported since the 5.2 magnitude earthquake struck early Friday morning; the most recent of which was a 2.2 magnitude earthquake Monday morning, said Tim Larson a geophysicist who monitors earthquakes at the Illinois State Geological Survey at the University.

Larson said that 9 aftershocks occurred within the first 3 hours after the initial earthquake.

Others have occurred every twelve hours or so, he added.

Thus far, the two largest aftershocks occurred at 10:14 a.m. Friday and 12:38 a.m. Monday. They measured 4.5 and 4.0 respectively on the Richter Scale.

“We are expecting that the aftershocks will diminish in frequency throughout this week,” Larson said in an e-mail. “However, there is a small chance of another magnitude 4 or greater aftershock.”

Brittany Abeijon contributed to this report.