After a hiatus of almost five months, blasting is about to resume at the Hanson Material Service quarry in McCook.
Blasting was halted late last year after a 3.2 magnitude tremor shook the area seconds after a routine blast had been completed. But after months of studying data and monitoring seismographs at the site, quarry officials announced Wednesday that blasting would resume Monday, March 17.
“After working with representatives from Northwestern University, the U.S. Geological Survey and the Illinois Department of Natural Resources, we do not have data that confirms any correlation between blasting by the quarry and the seismic event that occurred on Nov. 4, 2013,” said Michael Stanczak, vice president and general manager of the quarry, in a press release from Lehigh Hanson Inc., the Texas-based parent company of Hanson Material Service.
The tremor, which occurred just seven seconds after routine blasting at the quarry, was felt as far away as southern Wisconsin. In the immediate vicinity of the quarry, in places like Brookfield and Countryside, it shook buildings and reportedly caused some damage to structures.
Initially, the USGS attributed the tremor to the quarry blast itself. However, after further investigation it was determined that the blasting and tremor were two separate events. The area experienced a similar, less powerful, seismic event in the wake of blasting in 2010.
U.S. Congressman Daniel Lipinski, who represents the area where the quarry is located, called for an investigation into the cause of the earthquake. In December 2013, the USGS installed a seismograph at the quarry, which monitors seismic activity around the clock. A second seismograph was installed by the Illinois Department of Natural Resources, said Jeff Sieg, a spokesman for Lehigh Hanson Inc.
Both of those seismographs will remain in place at the quarry and will continue to monitor seismic activity.
“The quarry will continue to work closely with these parties to study its blasting operations going forward,” said Stanczak.
Hanson Material Service also hired a firm to perform independent seismic monitoring and review damage complaints related to the Nov. 4 tremor. That report is “near completion,” the company said.
According to Hanson Material Service, none of the damage claims it has reviewed resulted from the quarry’s blasting operations.