On the visibility of the inner-core shear wave phase PKJKP at long periods
Bibliographic record
Abstract
Stacks of over 90 000 long-period seismograms recorded by the global seismic networks resolve many seismic phases but fail to detect the inner-core shear phase PKJKP. We compare these results to synthetic seismograms computed for PREM using the spectral-element method and show that expected PKJKP amplitudes are over 10 times smaller than signal-generated ‘noise’ caused by high-order P surface multiples and reverberations from upper-mantle discontinuities. Indeed, PKJKP can only be seen in synthetic seismograms when differences are taken between two sets of synthetics generated from Earth models with slightly different inner-core shear velocities. These results suggest that routine observation of PKJKP is unlikely and that reported observations, if real, must have resulted from exceptional focusing effects or inner-core attenuation much less that current models.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 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".