The US Geological Survey originally reported it as a 3.7 magnitude earthquake with an epicenter of Indian Head Park, but has since changed the website to say it was a quarry blast in nearby Countryside Hills.
Residents in the west suburbs felt the shaking around 12:35 p.m. The tremors were classified as "light to weak" according to the earthquake.usg.gov shake map.
Check out the USGS ShakeMap.
No damage or injuries have been reported.
