Understanding subsidence in the Mississippi Delta region due to sediment, ice, and ocean loading: Insights from geophysical modeling
Bibliographic record
Abstract
Abstract The processes responsible for land surface subsidence in the Mississippi Delta (MD) have been vigorously debated. Numerous studies have postulated a dominant role for isostatic subsidence associated with sediment loading. Previous computational modeling of present‐day vertical land motion has been carried out in order to understand geodetic data. While the magnitudes of these measured rates have been reproduced, the model parameter values required have often been extreme and, in some cases, unrealistic. In contrast, subsidence rates in the MD on the 103 year timescale due to delta loading estimated from relative sea level reconstructions are an order of magnitude lower. In an attempt to resolve this conflict, a sensitivity analysis was carried out using a spherically symmetric viscoelastic solid Earth deformation model with sediment, ice, and ocean load histories. The model results were compared with geologic and geodetic observations that provide a record of vertical land motion over three distinctly different timescales (past 80 kyr, past 7 kyr, and past ~15 years). It was found that glacial isostatic adjustment is likely to be the dominant contributor to vertical motion of the Pleistocene and underlying basement. Present‐day basement subsidence rates solely due to sediment loading are found to be less than ~0.5 mm yr−1. The analysis supports previous suggestions in the literature that Earth rheology parameters are time dependent. Specifically, the effective elastic thickness of the lithosphere may be <50 km on a 105 year timescale, but closer to 100 km over 103 to 104 year timescales.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".