Editor's note: Your ProbateShark's fish brain is slow to react...but he does study history. The massive New Madrid earthquakes of 1812 - 1813 reversed the flow of the Mississippi River for 10 miles. Illinois has had a massive earthquake every 200 years prior and guess what?? It is about time. We should be careful about tinkering with quarry rocks... Lucius Verenus, Schoolmaster, ProbateSharks.com
The earth shook. But how? Why?
Monday's west suburban tremor is still a mystery
Woman says tremor causes home damage
November 4, 2013Lois Brown, a volunteer with Catnap from the Heart, was in a LaGrange home to help organize an estate sale for the Not-for-profit animal shelter. She says as a tremor shook the house and caused a pipe to burst. (Antonio Perez/Chicago Tribune)Geophysicist comments on quarry blast
November 4, 2013 2:05 PM CSTPaul Caruso of the US Geological Survey discusses the seismic event earlier in the western suburbs.
Skilling: Quarry blast causes earthquake-like tremors
November 4, 2013 2:10 PM CSTWGN's Tom Skilling talks about about a quarry blast that caused quake-like tremors in the Chicago-
Witness describes seismic blast in Hinsdale
November 4, 2013 2:19 PM CSTJames Oranga, Assistant Controller at the Hinsdale Bank & Trust, describes the scene in the basement of his workplace after tremors struck the western suburbs.
When nature called just before 1 p.m. Monday, security guard John Harbacek left his post at a shipping yard in McCook and headed over to a porta-potty.
His trip to the facilities turned out to be a little more exciting than normal.
First came a concussive blast from Federal Quarry next door to the yard. Seconds later, things got crazy.
"The whole thing was shaking," the 61-year-old Lyons resident said of the porta-potty. "I've been in there when people shake it as a joke, but this thing was lifting two, three inches off the ground."
The tremor, which had a 3.2 magnitude, shook homes and businesses — and likely a few more porta-potties — as far away as Wisconsin.
It also has sparked outrage from residents who live near the quarry and have complained about the blasting for years, including U.S. Rep. Daniel Lipinski, who asked the U.S. Department of Labor and the Bureau of Alcohol, Tobacco, Firearms and Explosives to investigate.
Officials from the U.S. Geological Survey, the Illinois Department of Natural Resources and Lehigh Hanson, the company that owns the quarry, plan to meet soon to compare data. For now, no one knows for sure what caused the tremor that followed the blast.
It wasn't an earthquake, said geophysicists at the USGS, who noted that the shock wave signature recorded by their instruments was typical of a quarry blast.
It wasn't the blast, said officials from the Illinois Department of Natural Resources, which found that data at the site showed the blast and subsequent tremor were separate events.
The conundrum has scientists like Tim Larson scratching their heads.
"This is kind of weird — the two pieces of information contradict each," said Larson, the senior geophysicist for the Illinois State Geological Survey.
Larson said that unlike earthquakes, which are recorded as large spikes when massive plates miles below the surface suddenly shift, blasts from quarries tend to look like little ripples. What made this tremor unique is that it had the force of an earthquake, but the vibrations were consistent with a quarry blast.
But the seven-second delay between blast and tremor remains a mystery.
"The question is whether you can have an earthquake that is triggered by a blast that also shows similar characteristics to a blast," Larson said.
USGS officials remain skeptical the tremor was caused by anything other than the blast but said they haven't seen the raw recordings taken by the quarry owner's equipment and are leaving open the possibility that there is another explanation.
"The evidence ... indicates the event was very shallow, which in our way of speaking means it was in the upper mile or two of the earth's crust," said Jim Dewey, research geophysicist emeritus with the agency. "The typical natural earthquake in the area would occur at a depth of more like five or 10 miles."
It is rare for quarry operations to cause earthquakes, Dewey said. He recalled once in New York where researchers concluded a series of small tremors were the result of a small fault that was able to shift as a quarry operation above it removed rock that had previously pinned the fault in place.
He said massive quakes can cause small tremors in quake-prone areas. But it's unlikely the force of Monday's blast could trigger a larger tremor.
While the USGS measures magnitude by the amount of energy released at the epicenter of a seismic event, seismographs at the quarry used a different measurement called Peak Particle Velocity (PPV) to record the velocity of the ground vibration.
According to Lehigh Hanson officials and the state Department of Natural Resources, the blast caused a PPV of .35 inches per second, well below the state-mandated limit of 1 inch per second. The subsequent tremor posted a PPV of 2.93 inches per second, more than eight times that of the initial explosion.
His trip to the facilities turned out to be a little more exciting than normal.
First came a concussive blast from Federal Quarry next door to the yard. Seconds later, things got crazy.
"The whole thing was shaking," the 61-year-old Lyons resident said of the porta-potty. "I've been in there when people shake it as a joke, but this thing was lifting two, three inches off the ground."
The tremor, which had a 3.2 magnitude, shook homes and businesses — and likely a few more porta-potties — as far away as Wisconsin.
It also has sparked outrage from residents who live near the quarry and have complained about the blasting for years, including U.S. Rep. Daniel Lipinski, who asked the U.S. Department of Labor and the Bureau of Alcohol, Tobacco, Firearms and Explosives to investigate.
Officials from the U.S. Geological Survey, the Illinois Department of Natural Resources and Lehigh Hanson, the company that owns the quarry, plan to meet soon to compare data. For now, no one knows for sure what caused the tremor that followed the blast.
It wasn't an earthquake, said geophysicists at the USGS, who noted that the shock wave signature recorded by their instruments was typical of a quarry blast.
It wasn't the blast, said officials from the Illinois Department of Natural Resources, which found that data at the site showed the blast and subsequent tremor were separate events.
The conundrum has scientists like Tim Larson scratching their heads.
"This is kind of weird — the two pieces of information contradict each," said Larson, the senior geophysicist for the Illinois State Geological Survey.
Larson said that unlike earthquakes, which are recorded as large spikes when massive plates miles below the surface suddenly shift, blasts from quarries tend to look like little ripples. What made this tremor unique is that it had the force of an earthquake, but the vibrations were consistent with a quarry blast.
But the seven-second delay between blast and tremor remains a mystery.
"The question is whether you can have an earthquake that is triggered by a blast that also shows similar characteristics to a blast," Larson said.
USGS officials remain skeptical the tremor was caused by anything other than the blast but said they haven't seen the raw recordings taken by the quarry owner's equipment and are leaving open the possibility that there is another explanation.
"The evidence ... indicates the event was very shallow, which in our way of speaking means it was in the upper mile or two of the earth's crust," said Jim Dewey, research geophysicist emeritus with the agency. "The typical natural earthquake in the area would occur at a depth of more like five or 10 miles."
It is rare for quarry operations to cause earthquakes, Dewey said. He recalled once in New York where researchers concluded a series of small tremors were the result of a small fault that was able to shift as a quarry operation above it removed rock that had previously pinned the fault in place.
He said massive quakes can cause small tremors in quake-prone areas. But it's unlikely the force of Monday's blast could trigger a larger tremor.
While the USGS measures magnitude by the amount of energy released at the epicenter of a seismic event, seismographs at the quarry used a different measurement called Peak Particle Velocity (PPV) to record the velocity of the ground vibration.
According to Lehigh Hanson officials and the state Department of Natural Resources, the blast caused a PPV of .35 inches per second, well below the state-mandated limit of 1 inch per second. The subsequent tremor posted a PPV of 2.93 inches per second, more than eight times that of the initial explosion.
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