When you live around a quarry you come to expect loud explosions and the earth moving right under your feet. But after Monday's blast and rumbling ground there was something else familiar: the response from Hanson Materials: "It wasn't our fault."
The claim that there was no connection between their land blasting and the earthquake is nearly identical to what Hanson executives claimed three years ago when the earthquake meters started hopping then.
Gut-jarring blasts such as this are common around suburban Chicago quarries-- at a south suburban limestone yard owned by Hanson Services, and at the company's quarry in southwest suburban McCook. At this quarry, in operation for more than a century, there are regular explosions.
"We do not believe there is any correlation between mining activities and the seismic event the USGS reported," said Jeff Brasuell, Hanson area manager.
That was what Hanson's manager said in September 2010, after a 2.7 tremor followed a blast here in McCook. And it is exactly what company executives are saying Monday, that this explosion and subsequent ground shaking are just a coincidence.
Some residents around here don't buy it. LaGrange resident Linda Lauterbach says she has kept this handwritten log of every blast and shock wave. Her research documents more than 40 blasts since mid-June, and some were "big and prolonged" after the explosion noise.
The company said Monday that the blasting was routine and that all readings were below regulatory limits.
Here is what they said three years ago when the same thing happened: "A part of our blasting process which we are doing several times a week. We use seismic equipment and we stay well below regulatory limits," said Jeff Brasuell, Hanson area manager.
The noise level from these blasts cannot exceed 144 on a decibel meter. During that resident's research she says the company-provided equipment peaked at 140, but she questions the margin of error. This is such an ongoing concern that there is actually an organization called the Lyons Township Quarry Council that tries to keep an eye on these claims and counterclaims.