Quake unlikely a precursor to disaster

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Thursday, February 11, 2010

Wars, tsunamis, the East Coast paralyzed by “snow-mageddon.”

And now an earthquake in Wisconsin, of all places?

Don’t connect those dots, experts advise. Quakes are rare here but not unheard of.

A quake centered in northern Illinois rumbled through just before 4 a.m. Wednesday. The U.S. Geological Survey at first said it was a 4.3-magnitude quake but later downgraded it to a 3.8, “which is still for us a fairly decent quake,” said Bob McCallister, a geology professor at UW-Rock County.

The recent quake that ravaged Haiti rated a 7.

“It’s unlikely to very unlikely for an earthquake to happen in this area that would actually cause damage,” said Prajukti Bhattacharyya, a UW-Whitewater geologist who is responsible for the fact that UW-W has a seismograph.

The UW-W instrument registers earthquakes from around the globe, including the recent one in Haiti.

“There’s no cause for panic,” Bhattacharyya said. “We’re not going to be the next Haiti anytime soon.”

Bhattacharyaa noted that earthquake damage depends not only on the strength of the quake but also the strength of the buildings and the density of the population.

People across southern Wisconsin and northern Illinois felt their houses shake and windows rattle, but no damage was reported.

“I was asleep, only to wake up to my bed shaking and moving away from my wall,” said Jennifer Johnson, rural Evansville.

“A picture frame had fallen off my shelf and shattered on the floor,” Johnson said in an e-mail.

Like many in the area, her first thought was a snowplow, “but the shaking was too powerful to be a snow plow.”

“I was scared at first, so scared that I called my mom,” Johnson said. “I have never felt an earthquake before. It was scary but yet somewhat interesting.”

Interesting is right.

Southern Wisconsin has had its share of minor tremors emanating from earthquakes to the south, but this quake, originating near Virgil, Ill., was different.

“It’s a total surprise,” said Philip Carpenter, a seismologist at Northern Illinois University, because the epicenter, about 55 miles south of Janesville in Kane County, has never produced an earthquake before.

“No one knew there was a fault there. We’ve never had an earthquake centered in this particular area, and we have 150 years of records,” Carpenter said in an NIU news release.

Northern Illinois has produced a number of quakes, including ones that were felt in southern Wisconsin in 2008, 2004 and 1999, Gazette records indicate.

Midwest earthquakes always raise the specter of the New Madrid fault zone, named for the Missouri town where massive quakes originated in 1812 and 1813.

This wasn’t one of those, “but when that one happens again, you’ve got to wonder what it’s going to be like, even this far north,” McCallister said.

Rock County’s Natural Hazard Mitigation Plan, approved in 2004, stated that the county has felt 22 earthquakes since 1899. Three more have been recorded since then.

Carpenter said two major faults have been identified in northern Illinois—the Sandwich fault and the Plum River fault—but both have been dormant for 150 years.

Carpenter indicated research is needed to learn the full story of the northern Illinois faults.

McCallister said this area has more immediate concerns than the potential for a serious earthquake.

“Maybe it puts into our mind a little bit of what a earthquake is like on a larger scale, like in Haiti,” McCallister said. “We look at it as a lark or an interesting tidbit to talk about, but if you’re on a major plate boundary, it’s something you have to think about as a way of life.”

Last updated: 12:57 pm Thursday, December 13, 2012

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