There have been 15 aftershocks in Illinois since Friday morning’s earthquake, including one early Monday morning.

The initial earthquake was a 5.2 magnitude at 4:37 a.m. Friday in southern part Illinois.

The earthquake then made its way to DeKalb in just one minute, said Philip Carpenter, professor of geology and environmental sciences.

The 15 aftershocks experienced from the earthquake all had a magnitude of 4.5 or less.

The aftershocks include one of 4.0 magnitude at 12:40 a.m. Monday morning near Mt. Carmel, Ill.

Carpenter said aftershocks are due to broken faults in the ground.

“When an earthquake happens, a break in a fault is made. While the fault is still broken, aftershocks are experienced,” he said.

He expects there to be more aftershocks in the next few days.

Carpenter said earthquakes are not entirely uncommon in Illinois.

“About every five years, we feel an earthquake,” he said. “This is something that usually occurs in southern Illinois.”

Carpenter said this is because the southern part of Illinois is more seismically active.

He also said that an earthquake having a magnitude around 5.0 is not a serious one.

“A magnitude of five is typically considered a moderate earthquake,” Carpenter said.

The last notable earthquakes that happened in Illinois were in 2002, with a magnitude of 5.1, and 1987, with a magnitude of 5.0.