Earthquakes of April 18, 2008 and Aftershocks

Early in the morning of April 18, an earthquake occurred across southeast Illinois.  A report from the National Earthquake Information Center indicates that the quake, which occurred at 4:37 am CDT, was centered 5 miles north-northeast of Bellmont (38.450°N, 87.890°W) in Wabash County, or approximately 22 miles south southeast of Olney.  This quake measured 5.2 on the Richter Scale and was reportedly felt as far away as Kansas, Georgia and the upper peninsula of Michigan.  It was located at a depth of approximately 7.2 miles.  Details on this quake can be found by clicking here.  If you felt this quake, you can click on the link "Did You Feel It?" and report your observations, which will be added to this map:
Earthquake reports for initial April 18 earthquake

Later that morning, an aftershock of 4.6 magnitude occurred in the same general area.  It was centered 7 miles east-southeast of West Salem (38.483°N, 87.891°W) in Wabash County, or abour 40 miles north-northwest of Evansville, Indiana. 

The location of these two earthquakes is shown below (click images to enlarge):

Since the initial quake, over 20 aftershocks have been recorded.  A summary of the more notable earthquakes as of the morning of April 22:

Date Time (CDT) Mag. Location
April 18 4:37:00 AM 5.2 5 miles north-northeast of Bellmont (38.45 N, 87.89 W)
April 18 4:59:31 AM 2.6 4 miles north-northwest of Mount Carmel (38.469 N, 87.795 W)
April 18 5:36:33 AM 3.4 6 miles west-northwest of Mount Carmel (38.46 N, 87.86 W)
April 18 6:55:58 AM 2.6 4 miles north-northeast of Bellmont (38.44 N, 87.89 W)
April 18 10:14:16 AM 4.6 7 miles northwest of Mount Carmel (38.478 N, 87.869 W)
April 18 10:05:53 PM  2.7  4 miles north-northeast of Bellmont (38.44 N, 87.89 W) 
April 19 11:55:17 AM   2.8  4 miles north of Bellmont (38.44 N, 87.90 W) 
April 20 12:02:42 AM  2.8 5 miles west-northwest of Mount Carmel (38.44 N, 87.85 W) 
April 21 12:38:29 AM  4.0  7 miles northwest of Mount Carmel (38.483 N, 87.857 W) 


The earthquakes occurred in the Wabash Valley Seismic Zone. 

 Historic Illinois Earthquakes (Magnitude 4.0 or stronger)...

M5.5 1891 Sep 27 by Aden (Hamilton County, southern IL) 
M5.4 1968 Nov 9 by Texas City (Saline County, southern IL)
M5.2 2008 Apr 18 by Bellmont (Wabash County, southern IL)
M5.2 1909 Jun 26 by Bowling Brook (Will County, northern IL)
M5.1 1838 Jun 9 by Walnut Hill (Marion County, southern IL)
M5.1 1857 Oct 8 by Boulder (Clinton County, southern IL)
M5.0 1987 June 10 by Claremont (Richland County, southern IL)
M4.7 1909 Jul 19 by Kilbourne (Cass County, central IL)
M4.6 2008 Apr 18 by Mount Carmel (Wabash County, southern IL) 
M4.4 1922 Mar 22 by Eldorado (Saline County, southern IL)
M4.1 1972 Sep 15 by Holcomb (Ogle County, northern IL)
M4.1 2004 Jun 28 by Troy Grove (La Salle County, northern IL)
M4.0 2008 Apr 21 by Mount Carmel (Wabash County, southern IL) 







Data from 
Illinois State Geological Survey

Some links you may find interesting:

Images (click to enlarge; all photos by Lawrence County Emergency Management Agency):

Bricks fell off a building.  Photo by Lawrence County EMA

Bricks shaken loose.  Photo by Lawrence County EMA

Chimney and car damage.  Photo by Lawrence County EMA.

Broken car window in Lawrenceville, caused by falling bricks.  Photo by Lawrence County EMA.

Cracks at the Lawrence County Courthouse in Lawrenceville.  Photo by Lawrence County EMA.

Brick facade broken off a building in Bridgeport.  Photo by Lawrence County EMA.
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