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:
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. Details on this particular quake can be found by clicking here.
The location of these two earthquakes is shown below (click images to enlarge):
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Seismograph displays from Olney (courtesy of the Center for Earthquake Research and Information), click image to enlarge:
 April 18, midnight to noon |
 April 21, midnight to noon |
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) |
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Data from Illinois State Geological Survey
Some links you may find interesting:
- Damaging Illinois Earthquakes (Illinois State Geological Survey)
- Illinois Earthquake History (Illinois State Geological Survey)
- Center for Earthquake Research and Information page on this earthquake
- National Seismic Hazard Maps (U.S. Geological Survey)
Images (click to enlarge; all photos by Lawrence County Emergency Management Agency):
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