Influence of Glacial Isostatic Adjustment on Intraplate Stress and Seismicity in Eastern North America in the Presence of Pre‐Existing Weak Zones
Bibliographic record
Abstract
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 ( 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 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.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".