Cataloging the 1811-1812 New Madrid, Central U.S., Earthquake Sequence

Abstract

The three principal New Madrid, central U.S., mainshocks of 1811-1812 were followed by extensive aftershock sequences that included numerous felt events. Although no instrumental data are available for the sequence, historical accounts provide information that can be used to estimate magnitudes and locations for the large aftershocks as well as the mainshocks. Several detailed eyewitness accounts of the sequence provide sufficient information to identify times and rough magnitude estimates for a number of aftershocks that have not been analyzed previously. I also use three extended compilations of felt events to explore the overall sequence productivity. Although one generally cannot estimate magnitudes or locations for individual events, the intensity distributions of recent, instrumentally recorded earthquakes in the region provide a basis for estimation of the magnitude distribution of 1811-1812 aftershocks. The distribution is consistent with a b-value distribution. I estimate Mw 6-6.3 for the three largest identifiable aftershocks, apart from the so-called dawn aftershock on 16 December 1811. INTRODUCTIONThe 1811-1812 New Madrid earthquake sequence included three well-documented mainshocks that have been described and analyzed in considerable detail (e.g., Mitchill 1815;Fuller 1912;Nuttli 1973;Penick 1981;Street 1982Street , 1984Johnston 1996b;Hough et al. 2000;Bakun and Hopper 2004a). The three principal mainshocks occurred at approximately 02:15 local time (LT) on 16 December 1811; around 07:15 LT on 23 January 1812, and approximately 03:00 LT on 7 February 1812 (henceforth NM1, NM2, and NM3, respectively). The so-called dawn aftershock on 16 December 1811 was also widely felt (e.g., Johnston 1996b; Hough et al. 2000). The magnitude estimates of the four principal events-i.e., the three mainshocks and the dawn aftershock-have been the subject of considerable debate, with published Mw estimates ranging from ~7 to >8 (e.g., Nuttli 1973;Johnston 1996b; Hough et al. 2000, Bakun andHopper 2004a).Each of the three mainshocks was followed by an energetic aftershock sequence. The aftershocks are not included in the National Center for Earthquake Engineering Research (NCEER) catalog of historical central/eastern U.S. earthquakes (Armbruster and Seeber 1992). Nor are aftershocks included in a more recent study (Bakun and Hopper 2004b), which presents locations and magnitudes for moderate historical earthquakes in the eastern/central U.S. but does not include any events prior to 1827.A number of eyewitness accounts from the New Madrid region document the unrest without providing much if any detail about individual events. Two eyewitnesses, Daniel Drake in Cincinnati, Ohio, and Jared Brooks in Louisville, Kentucky, kept detailed records of felt events, in both cases ranked by perceived relative severity of shaking. Drake's accounts were included as an appendix to a book published in 1815 (Drake 1815); Brooks's accounts were published posthumously (McMurtrie 1819). An additional account from the settlement of...

Toward a consistent model for strain accrual and release for the New Madrid Seismic Zone, central United States

“…We determine a rate of events separately using the historic catalog [ Seeber and Armbruster , 1991], which covers 1627–1985, and the modern instrumental catalog for 1974–2009. The historic catalog is updated to include the results of this study as well as the additional 1811–1812 aftershocks and triggered earthquakes analyzed by Hough [2009]. Figure 8 presents the magnitude distribution for the combined instrumental and historical catalogs.…”

“…One can revisit the long‐term distribution of NMSZ magnitudes given the magnitude estimates determined by this study as well as revised magnitudes for several large aftershocks of the 1811–1812 sequence [ Hough , 2009]. For the large events, the uncertainties associated with intensity assignments and the attenuation relation are generally dependent between events.…”

Ground‐Motion Simulations of 1811–1812 New Madrid Earthquakes, Central United States

“…Contemporary accounts document a severe aftershock early on the morning (∼2∶15 a.m. local time) of 16 December 1811, and two additional mainshocks on 23 January and 7 February 1812 (∼9∶15 a.m. and ∼3∶45 a.m. local time, respectively), followed by a year of smaller but noticeable shocks (Fuller, 1912;Hough, 2004). Each of the three mainshocks was followed by an energetic aftershock sequence, including several in the M 6.0-6.3 range (Hough, 2009). Henceforth, we will refer to the three principal events in December, January, and February as NM1, NM2, and NM3, respectively, following Johnston (1996) and Hough (2004).…”

Microseismic Activity and Basement Controls on an Active Intraplate Strike‐Slip Fault, Ceres–Tulbagh, South Africa

“…This earthquake sequence, of which at least three events have estimated moment magnitude (M w ) above 7.0 (Hough, 2009), occurred within a Late Proterozoic to Early Cambrian failed intracontinental rift (Thomas, 1991). Within this rift, recently active faults appear to form an irregular geometry involving dextral strike-slip faulting and an unstable, young, compressional stepover (Schweig and Ellis, 1994).…”