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Magnitude Estimates of Two Large Aftershocks of the 16 December 1811 New Madrid Earthquake

Hough, Susan E. and Martin, Stacey (2002) Magnitude Estimates of Two Large Aftershocks of the 16 December 1811 New Madrid Earthquake. Bulletin of the Seismological Society of America, 92 (8). pp. 3259-3268. ISSN 0037-1106. doi:10.1785/0120010226.

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The three principal New Madrid mainshocks of 1811-1812 were followed by extensive aftershock sequences that included numerous felt events. Although no instrumental data are available for either the mainshocks or the aftershocks, available historical accounts do provide information that can be used to estimate magnitudes and locations for the large events. In this article we investigate two of the largest aftershocks: one near dawn following the first mainshock on 16 December 1811, and one near midday on 17 December 1811. We reinterpret original felt reports to obtain a set of 48 and 20 modified Mercalli intensity values of the two aftershocks, respectively. For the dawn aftershock, we infer a M_W of approximately 7.0 based on a comparison of its intensities with those of the smallest New Madrid mainshock. Based on a detailed account that appears to describe near-field ground motions, we further propose a new fault rupture scenario for the dawn aftershock. We suggest that the aftershock had a thrust mechanism and occurred on a southeastern limb of the Reelfoot fault. For the 17 December 1811 aftershock, we infer a M_W of approximately 6.1 ± 0.2. This value is determined using the method of Bakun et al. (2002), which is based on a new calibration of intensity versus distance for earthquakes in central and eastern North America. The location of this event is not well constrained, but the available accounts suggest an epicenter beyond the southern end of the New Madrid Seismic Zone.

Item Type:Article
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Hough, Susan E.0000-0002-5980-2986
Additional Information:© 2002 by the Seismological Society of America. Manuscript received 23 August 2001. We thank Bill Bakun, Paul Tapponier, Jim Dewey, and Aron Meltzner for helpful comments and suggestions that greatly improved the manuscript, and John McBride, Joan Gomberg, and Jose Pujol for constructive reviews; Figures 1, 2, and 4 were generated using GMT software (Wessel and Smith, 1991). Research by S. Martin was supported by the Southern California Earthquake Center (SCEC). SCEC is funded by NSF Cooperative Agreement EAR-8920136 and USGS Cooperative Agreements 14-08-0001-A0899 and 1434-HQ-97AG01718. The SCEC Contribution Number for this article is 605.
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSF Cooperative AgreementEAR-8920136
USGS Cooperative Agreement14-08-0001-A0899
USGS Cooperative Agreement1434-HQ-97AG01718
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Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center (SCEC)605
Issue or Number:8
Record Number:CaltechAUTHORS:20140804-144635533
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Official Citation:Susan E. Hough and Stacey Martin Magnitude Estimates of Two Large Aftershocks of the 16 December 1811 New Madrid Earthquake Bulletin of the Seismological Society of America, December 2002, v. 92, p. 3259-3268, doi:10.1785/0120010226
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47925
Deposited By: Ruth Sustaita
Deposited On:04 Aug 2014 21:56
Last Modified:10 Nov 2021 17:51

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