The earth rattled in the Chicago area Monday afternoon, but it turned out the fault (so to speak) was with man and not nature.
WGN-TV reports that a "shot" blast at Hanson Materials in suburban Hodgkins, Ill., was to blame for what the U.S. Geological Survey recorded as a magnitude-3.2 earthquake at 12:35 p.m. CST Monday. Initially, the USGS had rated the magnitude as 3.7.
The USGS website received reports of shaking across many of Chicago's western and southwestern suburbs, as well as parts of the city itself, generally within a 15-mile radius of the quarry blast. Most of these reports were characterized as weak or light. A few spotty reports of shaking came in from the northwestern suburbs as well. No serious damage was reported.
Two major quarries operate in the vicinity of the reported epicenter. According to Google Maps, less than a mile separates the Hanson Materials site from the larger McCook Quarry, both located about 15 miles west-southwest of downtown Chicago.
Jeff May, senior area operations manager for Vulcan Materials Company, which operates the McCook Quarry, confirmed his company did not conduct any blasting activity Monday.
(WATCH: Chicago Forecast)
Joshua Robbins, spokesman for Vulcan, told weather.com that quarries typically keep close tabs on the impact of their blasts, which in the industry are called "shots."
"The shots are all measured. There are seismographs. Quarries typically measure it at multiple locations," Robbins said. "Each shot is recorded ... usually at multiple points."
He explained that quarry shots are typically done by drilling holes into the limestone rock and using ammonium nitrate fuel oil mixture to do the blasting. He noted that most states have a Department of Natural Resources that regulates such activity.
Robbins said it would be hard to imagine a quarry blast being large enough to cause structural damage. "In my company, we send out structural engineers to evaluate claims of blast damage."
No comments:
Post a Comment