Constraints on Inner Core Anisotropy Using Array Observations of P′P′
Bibliographic record
Abstract
Abstract Recent studies of PKPdf travel times suggest strong anisotropy (4% or more) in the quasi‐western inner core hemisphere. However, the availability of paths sampling at low angles to the Earth's rotation axis (the fast axis) is limited. To augment this sampling, we collected a travel time data set for the phase P′P′df (PKPPKPdf), for which at least one inner core leg is quasi‐polar, at two high latitude seismic arrays. We find that the inferred anisotropy is weak (on the order of 0.5 to 1.5%), confirming previous results based on a much smaller P′P′ data set. While previous models of inner core anisotropy required very strong alignment of anisotropic iron grains, our results are more easily explained by current dynamic models of inner core growth. We observe large travel time anomalies when one leg of P′P′df is along the South Sandwich to Alaska path, consistent with PKPdf observations, and warranting further investigation.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 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".