Illinois earthquake actually a quarry blast

(UPI) -- The U.S. Geological Survey says the reported 3.2 magnitude earthquake that struck Illinois Monday was in fact a quarry blast.

The agency said the event took place around 12:35 p.m. in Cook County.

"It's not an earthquake," said Don Blakeman, a geophysicist with the U.S. Geological Survey. "We're pretty sure it's a large quarry blast."

Blakeman added that a blast caused the tremor because there's a limestone quarry in nearby McCook.

More than 600 people reported the tremor to federal officials.

No injuries or damages have been reported thus far. Earthquakes between 2.5 magnitude and 3.0 are among the smallest felt by humans.