Recurrence rates and b values for global in-slab earthquakes
Bibliographic record
Abstract
The b value, a measure of the relative number of large and small earthquakes, for the Cascadia subduction zone off the coast of southern British Columbia is low (0.44-0.74) when compared to other seismic zones in Canada and to global averages (0.65-1.1.0). The hazard for this region is dominated by in-slab earthquakes, or those that occur within the subducting slab rather than at the slab interface. It has not been known whether the low b value is a characteristic of in-slab earthquakes or whether Cascadia is truly anomalous. This study evaluates in-slab earthquakes worldwide and finds that on average the b values are comparable to those for other types of earthquakes and suggests that Cascadia is unusual. These results are based on earthquakes of magnitude 5.5 or greater obtained from a global database, which has sufficient information to separate in-slab events from slab interface and shallow crustal earthquakes in the same subduction zone. Regional databases would be useful for extending the magnitude range studied but generally do not have the resolution required to reliably separate the events. We compare the b values and magnitude 7 recurrence intervals to physical properties of the subduction zones, such as age, dip angle and rate of subduction and find no obvious correlations.
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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 | 0.001 | 0.012 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| 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) | 0.003 | 0.001 |
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".