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

Mantle-to-surface contributions to heterogeneous stress fields in the Central and Eastern US

Paper number: 35-9
Program: Technical Sessions
Time: 10:45 AM – 11:00 AM

Authors

Abstract

The Central and Eastern United States (CEUS), located in the cratonic interior far from active plate boundaries, exhibits ongoing seismicity and a complex near-surface stress state, most prominently manifested by the New Madrid Seismic Zone and the East Tennessee Seismic Zone. While several local and plate-boundary mechanisms have been proposed to explain this enigmatic deformation, the relative contributions of these sources remain poorly quantified. In this study, we address this question using self-consistent geodynamic models. We develop instantaneous 3-D numerical models for the CEUS incorporating (1) surface topography; (2) crustal structure and densities from CRUST1.0; (3) lithospheric thermal and compositional structure from CAM2022; (4) sub-lithospheric density and viscosity variations derived from CUSRA2021 tomography; (5) major faults as low-viscosity zones; and (6) the velocity boundary conditions extracted from a global mantle convection model. We build our models with the community geodynamics code ASPECT and implement this comprehensive dataset. We explore the model's sensitivity to some of these stress sources and identify the best-fitting model with respect to the observed geodetic surface motions and maximum horizontal stress directions across the CEUS. We also assess the contributions from the melting of the Laurentide ice sheet to the north and from the sedimentation in the Gulf of America to the south. 

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

doi: 10.1130/abs/2026SE-411746

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