A quarry blast, not an earthquake
USGS: Shaking a quarry blast, not earthquake
INDIAN HEAD PARK (AP) – The U.S. Geological Survey says the shaking with a measured magnitude 3.2 in northern Illinois was a blast and not an earthquake.
USGS geophysicist Don Blakeman also says it appears Monday afternoon’s blast came from within a rock quarry but that the exact location of the blast had not yet been determined. He says that all indications so far leads experts to believe that the blast came from the quarry. That includes that the epicenter is in an area close to the quarry.