email: ckoplien@todaystmj4.com
Did you feel the earth move?!?
It was an earthquake.
The quake was centered in far southeast Illinois, but it was felt way up here in Wisconsin.
We began receiving phone calls here at the station this morning around 4:40am from people wondering what was going on.
Person after person was reporting their bed shaking, or their dishes rattling, or their cats meowing. Sure enough, before long we got confirmation from the United States Geological Survey (USGS - the people who monitor the earth's rockin' and rollin') that there had been an earthquake.
It was centered about 60 miles north of Evansville, Indiana...or near West Salem, Illinois. That's about 350 miles south of Milwaukee. Even at that distance, lots of people here felt it.
I didn't feel it...and I'm rather bummed about that. I was here at the station when it happened...which the USGS is officially listing at 4:37am. At that point, I'm am in full "sprint-mode", trying desperately to get everything ready go on TV at 5:00am.
Nobody in the building here felt it. (The solid, bedrock foundation on which TODAY'S TMJ4 sits protected us. Trust TODAY'S TMJ4.) Anyway, I've never felt an earthquake before. I'd like to. Not one of those mammoth, fall-into-the-ocean California earthquakes...just a little rumbler like this morning's.
The USGS says the quake registered 5.2 on the Richter Scale. That's a good-sized quake. In fact, according to the USGS, only 1 other quake has ever occurred in that area that was stronger. It was a 5.4 quake in 1968.
The quake was reportedly felt as far north as Peshtigo in Wisconsin...a town north of Green Bay. The quake was also felt as far away as Des Moines, Indianapolis, and in Chicago, where it reportedly caused the skyscrapers to sway a little.
It is believed that the quake originated in an area called the "Illinois Basin-Ozark Dome" region.
This area is just north of the more well known, "New Madrid Seismic Zone". The "Illinois Basin-Ozark Dome" covers parts of Illinois, Indiana, Kentucky, Missouri and Arkansas. Earthquakes are not uncommon in that region. Small quakes occur there a couple times per year. Quakes causing moderate damage have struck parts of the region about once every 10 to 20 years.
Earthquakes that occur in the central U.S. are generally felt over a larger region than those that occur in the western U.S. That is because of the solid bedrock on which the central U.S. sits. The bedrock tranfers the energy from the center of the quake much farther than the softer rocks and soils below ground out west. This explains why we in Wisconsin felt the shaking.
According to the website of the University of Wisconsin-Milwaukee Department of Geosciences, the following earthquakes have been felt in Milwaukee...the list indicates the date, location of the center, and the Richter Scale measurement...
--April 24, 1867: eastern Kansas, 5.1.
--Oct. 20, 1870: Canada, Montreal to Quebec, 6.0?
--Aug. 31, 1886: Charleston, S.C., 6.7.
--Oct. 31, 1895: southeastern Missouri, 5.9.
--May 26, 1909: northern Illinois, 5.1.
--Feb. 28, 1925: southeastern Quebec, 7.0.
--March 2, 1937: west-central Ohio, 5.0.
--March 8, 1937: west-central Ohio, 5.4.
--Sept. 4, 1944: Canada-western New York, 5.8.
--May 6, 1947: Milwaukee, 4.0.
--Aug. 9, 1947: south-central Michigan, 4.6.
--Nov. 9, 1968: southern Illinois, 5.5.
--Sept. 15, 1972: northern Illinois, 4.5.
--July 27, 1980: northeastern Kentucky, 5.1.
--Jan. 31, 1986: northeastern Ohio, 5.0.
--June 10, 1987: southeastern Illinois, 5.0.
--Nov. 25, 1988: southeastern Quebec, 6.0.
--Sept. 25, 1998: Pennsylvania-Ohio border, 5.2.
--June 18, 2002: Evansville, Ind., 5.0.
--June 28, 2004: northern Illinois. 4.2.
--April 18, 2008: West Salem, Ill.: 5.2.
To accurately compare the strength of earthquakes, it's important to understand how the Richter Scale works. A difference in 1 whole number is a difference in strength of 10 times. For example, a quake the registers 5.0 is 10 times stronger than one that registers 4.0.
Or, to use a recent example, remember the big quake in near San Francisco in 1989? The one that occurred during the World Series? That registered 6.9. With this morning's quake registering 5.2, there's a difference of 1.7. That makes the San Francisco quake around 17 times stronger than the one that occurred this morning.
My sister emailed me this morning, indicating that she was happy to find out that what she felt was an earthquake. She had thought she was crazy. Nope, none of you are. (Not about that anyway.)
