The U.S. Geological Survey is now reporting a magnitude 3.2 seismic event struck Illinois on Nov. 4.
"Scientists are investigating the event to determine whether it was an earthquake or a blast from a nearby quarry," the most recent updated from the USGS states.
The epicenter of this seismic event occurred in a southwest suburb of Chicago, about 15 miles from the downtown city center, the USGS states.
UPDATE 1:45 p.m. Monday
The National Weather Service is reporting the shaking felt today in Chicagoland was due to a quarry blast.
The USGS had attributed the 3.7 magnitude shaking centered in Indian Head Park to a blast at Hanson Material Service Co.'s quarry in McCook.
Check back to Patch later for more details (to see if this changes back to an earthquake!).
Original Story 1:23pm
The U.S. Geological Survey is reporting a magnitude 3.7 earthquake took place Monday, Nov. 4, at 12:35 p.m. in the suburbs of Chicago.
The epicenter of the quake, the USGS reports, was in Indian Head Park.
Police and the National Weather Service began receiving calls of shaking felt by residents living in Hinsdale, Willowbrook, Des Plaines and Willowsprings at about 12:40 p.m., according to NBC News Chicago.
At first, officials with the Hinsdale Fire Department attributed the shaking to activity from a nearby quarry, but the USGS confirmed an earthquake struck at 12:35:34 p.m. CT., NBC reports.