Influence of Glacial Isostatic Adjustment on Intraplate Stress and Seismicity in Eastern North America in the Presence of Pre-Existing Weak Zones
Creators
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1.
California Institute of Technology
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2.
Jet Propulsion Lab
Abstract
Eastern North America has hosted significant historical earthquakes, where seismicity clusters along tectonically inherited structures. Using the spherical finite-element code CitcomSVE and fully 3D viscosity structure, we model the intraplate stress response to glacial isostatic adjustment (GIA) using ICE-6G, both with and without low-viscosity intraplate weak zones. We find that present-day GIA-induced stresses are generally small (<2 MPa across most of eastern North America), both at present day and during deglaciation, and can locally reach 3–4 MPa where weak zones are present. Associated S_(Hmax) rotations are limited to ±1°, which are insignificant relative to the spread of observed stress data and far smaller than the continental-wide clockwise rotations obtained from mantle-flow models. However, GIA can still locally modify fault stability. In the New Madrid Seismic Zone, GIA promotes stability on the Reelfoot thrust fault while making NE-SW strike-slip faults less stable, suggesting a role in modulating present-day seismicity patterns but not in triggering the 1811–1812 sequence. In the Western Quebec Seismic Zone, GIA increases Coulomb failure stress (CFS) on the Timiskaming Fault and nearby faults, but changes in CFS in the Charlevoix Seismic Zone are negligible at present day and only marginally higher during deglaciation. Overall, GIA perturbs CFS by only a few MPa, insufficient to independently drive fault failure under tectonic background stress (TBS) conditions derived from mantle flow models, which dominate regional-to-continental intraplate stress. However, alternate lithospheric viscosity structures and TBS states can greatly enhance GIA stresses and their impact on faulting in the crust.
Copyright and License
© 2025 The Author(s). Geochemistry, Geophysics, Geosystems published by Wiley Periodicals LLC on behalf of American Geophysical Union. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Acknowledgement
We thank Shijie Zhong and Tao Yuan for providing the CitcomSVE code used to perform this research and for their assistance and thoughtful discussion on both the code-base and GIA research in general. We thank the reviewers, Rebekka Steffen and Sophie Coulson, for their incredibly detailed review and insightful commentary and questions. Their suggestions helped greatly improve the manuscript and the results of this paper. We also thank Mark Simons, Joann Stock, Zach Ross, and Michael Watkins for their helpful discussion and commentary on this research and the original dissertation work on which it is based. This work was supported in part by an NSF GRFP Fellowship to E. Hightower under award DGE-1745301, as well as USGS contract G19AC00125 and the Caltech President's and Director's Research and Development Fund (PDRDF). Computations were performed on the NSF-supported compute cluster Anvil at Purdue University under NSF ACCESS award EAR160027 and Computational Infrastructure for Geodynamics (CIG) Science Gateway and Community Codes for the Geodynamics Community, ACCESS award MCA08X011.
Data Availability
The Supporting Information S1 includes data sets containing model inputs and outputs, as well as scripts and other data sets/files needed for making the figures presented in the paper. These data are available from the CaltechDATA repository https://data.caltech.edu/records/xx010-6m027 (https://doi.org/10.22002/xx010-6m027). These include the 3D viscosity fields, the modeled stress tensor, the stress magnitudes, and the S_(Hmax) orientations. The temperature field and lithospheric thermal model used to derive the viscosity fields and the fault segment data used to compute the CFS are available in the data repository for Hightower et al. (2024). All model inputs and outputs from the mantle flow models referenced in this paper and a copy of CitcomS are available in the (Hightower et al., 2024) repository as well. Figures were made using either Python or GMT 6 (or PyGMT) (Wessel et al., 2019).
CitcomSVE v.3.0 (Yuan et al., 2025) is an open-source publicly available surface loading code maintained by Shijie Zhong and collaborators and available from his GitHub repository at https://github.com/shjzhong/CitcomSVE. The Supporting Information S1 also includes a copy of the version of CitcomSVE used, as well as pre- and post-processing scripts for the stress output.
The seismic velocity model (TX2019slab, Lu et al., 2019) used to constrain the temperature and hence viscosity fields used in the models is freely available from IRIS at http://ds.iris.edu/ds/products/emc-tx2019slab/. Stress data is available from the World Stress Map Project at https://www.world-stress-map.org/download. Data on rift geometries (polygons) and geology used to construct the weak zone input is available from the Central Eastern United States Seismic Source Characterization for Nuclear Facilities database (https://ceus-ssc.epri.com/GIS_Database).
Supplemental Material
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Geochem Geophys Geosyst - 2025 - Hightower - Influence of Glacial Isostatic Adjustment on Intraplate Stress and Seismicity.pdf
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Additional details
Related works
- Is supplemented by
- Supplemental Material: https://agupubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1029%2F2025GC012290&file=2025GC012290-sup-0001-Supporting+Information+SI-S01.pdf (URL)
- Dataset: https://data.caltech.edu/records/xx010-6m027 (URL)
- Dataset: 10.22002/xx010-6m027 (DOI)
- Software: https://github.com/shjzhong/CitcomSVE (URL)
Funding
- National Science Foundation
- DGE‐1745301
- United States Geological Survey
- G19AC00125
- California Institute of Technology
- President's and Director's Research and Development Fund (PDRDF) -
- National Science Foundation
- EAR160027
- National Science Foundation
- MCA08X011
Dates
- Accepted
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2025-09-15
- Available
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2025-09-27Version of record online
- Available
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2025-09-27Issue online