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Scientific overview and historical context of the 1811-1812 new Madrid earthquake sequence

Annals of Geophysics

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DOI: 10.4401/ag-3318

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Abstract

The central and eastern United States has experienced only 5 historic earthquakes with Mw 7.0, four during the New Madrid sequence of 1811-1812: three principal mainshocks and the so-called «dawn aftershock» following the first mainshock. Much of the historic earthquake research done in the United States has focused on the New Madrid Seismic Zone (NMSZ), because the largest New Madrid earthquakes may represent the archetype for the most damaging earthquakes to be expected in intraplate regions. Published magnitude values ranging from 7.0 to 8.75 have generally been based on macroseismic effects, which provide the most direct constraint on source size for the events. Critical to the interpretation of these accounts is an understanding of their historic context. Early settlments clustered along waterways, where substantial amplification of seismic waves is expected. Analyzing the New Madrid intensity values with a consideration of these effects yields preferred values of Mw 7.2-7.3, 7.0, and 7.4-7.5 for the December, January, and February mainshocks, respectively, and of 7.0 for the «dawn aftershock». These values are consistent with other lines of evidence, including scaling relationships. Finally, I show that accounts from the New Madrid sequence reveal evidence for remotely triggered earthquakes well outside the NMSZ. Remotely triggered earthquakes represent a potentially important new wrinkle in historic earthquake research, as their ground motions can sometimes be confused with mainshock ground motions.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Scientific overview and historical context of the 1811-1812 new Madrid earthquake sequence
Series title:
Annals of Geophysics
DOI:
10.4401/ag-3318
Volume
47
Issue:
2-3
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Annals of Geophysics
First page:
523
Last page:
537
Number of Pages:
15