Variations in Seismic Wave Speed and <i>V</i><sub><i>P</i></sub>/<i>V</i><sub><i>S</i></sub> Ratio in the North American Lithosphere
Bibliographic record
Abstract
Abstract Seismic wave speed is controlled by a number of factors, including temperature and chemical composition, as well as the presence of volatiles and partial melt. Tomography provides a powerful constraint on wave speed variations, but if only VP or VS variations are imaged, it is challenging to separate the competing effects of these factors and make a full interpretation of seismic anomalies. In this study, we generate models of variations in the VP/VS ratio, which introduce new constraints on geologic structures, compositions, and processes. We invert P and S wave arrival times, as well as Rayleigh wave phase velocities, utilizing the sensitivity of Rayleigh waves to both VP and VS to form mutually constrained but independent models of VP and VS structure at lithospheric depths below the continental United States and Southeastern Canada. From this we can examine variations in VP/VS, highlighting a distinct pattern of anomalies which are less readily observed in VP or VS alone. A clustering analysis is performed to relate 1‐D profiles of wave speed as a function of depth to tectonic provinces. While the first‐order structure of VP and VS appears to be dominated by the thermal contrast between the Eastern and Western United States, the strongest control over VP/VS ratio perturbations within the mantle lithosphere appears to be the presence of melt. Certain higher‐VP/VS anomalies within the cratonic interior may reflect compositional anomalies and variations in Moho structure. This work provides a continental‐scale framework for future quantitative analyses of thermal and compositional heterogeneity, and for targeted geologic interpretation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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) | 0.001 | 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".