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

Stress and Fault Slip Potential Maps of the New Madrid Seismic Zone and Surrounding Central United States

Paper number: 35-8
Program: Technical Sessions
Time: 10:30 AM – 10:45 AM

Authors

Abstract

The central United States has experienced multiple episodes of deformation, leaving behind faults of many different orientations. Modern crustal stress controls the seismogenic behavior of these faults. Although the central United States is some 5000 km from the nearest plate boundary, focal mechanisms and borehole stress data document significant variations in the directions and relative magnitudes of the principal stresses across the region. Embedded in an updated stress map of the continental United States, we present a new high-resolution stress map of the New Madrid and Wabash Valley Seismic Zones (NMSZ and WVSZ) and surrounding areas. Generally, the central U.S. is characterized by strike-slip faulting with minor secondary compression (Simpson’s AΦ≈1.55–1.75) and ~N55–75E maximum horizontal stress (SHmax). In the NMSZ and WVSZ, however, transpression is pervasive (AΦ≈1.80–2.10) and SHmax rotates clockwise to ~N70–90E. Because the local stress controls which fault orientations are reactivated, these stress variations have crucial impacts on seismogenic potential. Digitizing mapped faults throughout the region, we use the local stress models to quantify the slip potential of mapped faults in terms of normalized instability and Coulomb Failure Stress. These slip potential maps reveal that variations in fault activity are controlled by stress and not the other way around. For example, the gently dipping, south-striking Reelfoot thrust fault is nearly optimally aligned in its highly transpressive local stress field (AΦ≈2.06±0.07; SHmax N80E±3°), while inherited faults of similar orientation are comparatively stable in the more strike-slip stress field (AΦ≈1.80±0.04) along the Axial fault. We conclude by examining fault slip potential maps of the NMSZ; Fluorspar, Kentucky; the Thebes Gap area; Ste. Genevieve Seismic Zone; and WVSZ and discussing implications for paleoseismic targets and ongoing seismic hazard.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411752

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