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Liquefaction evidence for at least two strong Holocene paleo-earthquakes in central and southwestern Illinois, USA

Environmental and Engineering Geoscience

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Abstract

Two strong mid-Holocene earthquakes in Illinois have been documented by paleoliquefaction features such as clastic dikes, sills, and detachments of fine-grained sediment that sunk into liquefied sand. At least one paleo-earthquake occurred in central Illinois about 35 km NE of Springfield, probably sometime between 5,900 and 7,400 yr BP. Dike widths are as much as 0.4 m near the energy center of the earthquake. Outward from this center, dike widths attenuate and ultimately disappear at about 35 km. More than one paleo-earthquake is probably represented by liquefaction features near Springfield. Another paleo-earthquake that appears to have been centered about 65 km ESE of St. Louis, Missouri, occurred near 5,700 yr BP. The energy center is inferred as being in Illinois, and most likely near lowermost Shoal Creek where the meizoseismal region is defined by dikes as wide as 0.5 m and by a regional abundance of dikes. Dikes from this earthquake probably extend at least as far as 35 km from its inferred energy center. The earthquake near Shoal Creek and one earthquake near Springfield almost certainly exceeded M 6. The paleomagnitudes can be more closely bracketed by geotechnical testing and analysis, when used in conjunction with existing data.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Liquefaction evidence for at least two strong Holocene paleo-earthquakes in central and southwestern Illinois, USA
Series title:
Environmental and Engineering Geoscience
Volume
5
Issue:
2
Year Published:
1999
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental and Engineering Geoscience
First page:
133
Last page:
146
Number of Pages:
14