The April 18, 2008 Illinois earthquake: an ANSS monitoring success

Seismological Research Letters
By: , and 



The largest-magnitude earthquake in the past 20 years struck near Mt. Carmel in southeastern Illinois on Friday morning, 18 April 2008 at 09:36:59 UTC (04:37 CDT). The Mw 5.2 earthquake was felt over an area that spanned Chicago and Atlanta, with about 40,000 reports submitted to the U.S. Geological Survey (USGS) “Did You Feel It?” system. There were at least six felt aftershocks greater than magnitude 3 and 20 aftershocks with magnitudes greater than 2 located by regional and national seismic networks. Portable instrumentation was deployed by researchers of the University of Memphis and Indiana University (the first portable station was installed at about 23:00 UTC on 18 April). The portable seismographs were deployed both to capture near-source, high-frequency ground motions for significant aftershocks and to better understand structure along the active fault. The previous similar-size earthquake within the Wabash Valley seismic zone (WVSZ) of southeastern Illinois and southwestern Indiana was a magnitude 5.0 in June 1987. The seismicity associated with the WVSZ is thought to occur in a complex horst and graben system of Precambrian igneous and metamorphic units at depths between 12 and 20 km. Paleoliquefaction evidence suggests several major shaking events have occurred within the past 12,000 years (Munson et al. 1997).

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Publication type Article
Publication Subtype Journal Article
Title The April 18, 2008 Illinois earthquake: an ANSS monitoring success
Series title Seismological Research Letters
DOI 10.1785/gssrl.79.6.830
Volume 79
Issue 6
Year Published 2008
Language English
Publisher Seismological Research Letters
Publisher location El Cerrito, CA
Contributing office(s) National Earthquake Information Center
Description 14 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Seismological Research Letters
First page 830
Last page 843
Country United States
State Illinois
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