Regional seismic wave propagation (Lg & Sn phases) in the Amerasia Basin and High Arctic
Bibliographic record
Abstract
Observation of Lg seismic waves at regional distances has long been considered indicative of continental crust that is 30–40 km thick. This study updates an earlier assessment of Lg propagation efficiency to characterize continental or non-continental crust and related structures across the Amerasia Basin and surrounding continental areas of the high Arctic. Recent refraction surveys and receiver function studies provide crustal thickness estimates of 18–41 km for comparison. Among 7000 candidate earthquake–station pairs considered, no classic Lg phases (0.14–2 Hz) are observed to cross the Amerasia Basin (Canada Basin, Alpha-Mendeleev Ridge) efficiently, but lower frequency (0.035–0.17 Hz) arrivals with group velocities intermediate between Lg and Sn (sometimes called early Lg) are observed along many ray paths crossing the basin. The characteristic frequencies of these observed arrivals match well with those of synthetic waves propagated within models with thinned or pinched continental crust, such as crust characteristic of the North Sea, and thus suggest that most parts of the Amerasia Basin have a crustal thickness intermediate between that typical of thin continental and oceanic crust.
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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 | 0.001 | 0.001 |
| 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".