Kentucky Geological Survey Report of Investigations

Abstract

The damage and felt reports describing the New Madrid, Mo., earthquakes of 1811-12 need to be assessed in the historical context in which the events occurred. Log cabins in the frontier settlements along the lower Ohio River Valley, for example, were built with a rudimentary form of base isolation, and their response to the earthquakes should not be evaluated in the same way that a modern wood-frame or brick building would be.

Also, inaccuracies have crept into the databases used for estimating the epicenters and magnitudes of the earthquakes. For example, the magnitude of the December 16, 1811, earthquake has been based, in part, on the lack of damage to buildings built well after the occurrence of the 1811-12 events, and the locations and circumstances of some of the people who described their observations of earthquakes and aftershocks in December 1811 while traveling down the Mississippi River on flatboats have been incorrectly used to estimate modified Mercalli intensities.

This study indicates that the damage areas for the 1811-12 earthquakes have been underestimated, and favors an epicenter for the January 23, 1812, earthquake in the northern end of the new Madrid Fault Zone, and that the three aftershocks that some have suggested were triggered events centered in northeastern Kentucky or south-central Ohio were in fact centered in the New Madrid Seismic Zone.

Publication Date

2008

Series

Series XII

Report Number

Report of Investigations 20

Digital Object Identifier (DOI)

https://doi.org/10.13023/kgs.ri20.12

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