Modeling <i>S</i> wave amplitude patterns for events in the Kurile slab using three‐dimensional Gaussian beams
Bibliographic record
Abstract
The shear velocity structure of the subducted Kurile slab is modeled using shear wave amplitude residual spheres. We measure long‐period SH and ScSH phase amplitudes for 10 intermediate and deep focus earthquakes recorded at World‐Wide Standardized Seismograph Network and Canadian Seismic Network stations from 1967 to 1986. After correction for source radiation pattern, geometric spreading, and empirical receiver/upper mantle effects, the data for intermediate depth Kurile slab events show smoothly varying amplitude residual sphere patterns with low amplitudes concentrated in the direction down the slab dip. The data are modeled using three‐dimensional dynamic ray tracing and a three‐dimensional Gaussian beam method. Starting models are taken from previous P and S wave arrival time residual sphere studies. Three‐dimensional ray tracing indicates that ray patterns and resulting amplitudes are very sensitive to the depth extent of the slab and to the position of the event relative to the across‐slab velocity gradient. This sensitivity allows us to place some constraints on the Kurile slab geometry, position of each event within the slab, and penetration depth of coherent slab structure. Our final slab model is defined by an asymmetric error function that peaks at 4% higher velocity than Preliminary Reference Earthquake Model 25 km from the top of the slab. The total width of the thermal anomaly averages 140 km. The slab is tabular and extends to 670 km in the northern half of the Kurile subduction zone. In the southern half of the subduction zone the slab flattens along the 670 km discontinuity and deflects laterally, persisting to 750 km depth.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.001 | 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".