35 Recent advances in our understanding of the New Madrid seismic zone
Thorough understanding of the New Madrid seismic zone will require integration of observations relating to surface features, the crust and the upper mantle. All contributions are welcomed.
Wednesday, 11 March 2026
8:30 AM - 12:00 PM
RCC, 104
Quaternary Faulting in the Reelfoot Rift of the Northern Mississippi Embayment
Paper number: 35-1
Program: Technical Sessions
Time: 8:45 AM – 9:00 AM
Authors
Abstract
Geological and geophysical investigations into seismic hazards in the northern Mississippi embayment have uncovered many Cambrian Reelfoot rift faults that have reactivated during the Quaternary. The most intensively studied is the New Madrid seismic zone, which occurs on three Reelfoot rift faults that were responsible for the M 7.5, 7.3, and 7.7 earthquakes of 1811-1812. Additional “sleeping giants” have been identified that include the Commerce fault, Charleston uplift, Bluff Line fault, Joiner Ridge horst, Meeman-Shelby horst, Crowleys Ridge, Beedeville graben, Big Creek fault, and unnamed E-W normal faults that traverse the Reelfoot Rift. Most of these faults are buried under Mississippi River alluvium and thus difficult to assess. A successful technique for determining the Quaternary history of these faults has been through P and S wave seismic reflection and collecting dated cores on opposite sides of faults. However, this type of study has not been conducted on many of the sleeping giants. Vertical stress release through erosion has been proposed for Quaternary reactivation of the Reelfoot rift faults responsible for the New Madrid seismic zone. New research illustrates the Mississippi River Valley experienced as much as 180 m of denudation during Pleistocene and Holocene erosion. The Quaternary onset of Reelfoot rift fault activity may be related to the most recent 40 m of late Pleistocene and Holocene erosion. Erosion in two time periods within the last ~20 ka resulted in the removal of 40 m of sediment from atop many of the Reelfoot Rift faults that may have provided the trigger for fault reactivation. Determining the time when erosion occurred over the faults could be achieved with a series of drill cores. The age of the basal Mississippi River alluvium immediately overlying the faults would provide a time for when the faults were “uncorked”.
Geological Society of America Abstracts with Programs. Vol. 58, No. 1
doi: 10.1130/abs/2026SE-411565
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