Seismic velocity structure of the easternmost segment of the Gofar transform fault, East Pacific Rise
Bibliographic record
Abstract
The fast-slipping (~ 14 cm/yr) Gofar transform fault (GTF) East Pacific Rise has three active segments G1 to G3 from east to west. These fault segments produce large earthquakes (MW ~ 6.0) quasi-periodically every five to six years (Figure 1). Interestingly, large earthquakes rupture the same 20-km long fault patches separated by a ~ 10-km rupture barrier zone, implying along-strike variations in fault zone material properties (McGuire et al. 2012). This further suggests that rupture patches and barrier zones remain stable over multiple seismic cycles. Here, we jointly invert P- and S-wave travel times, recorded at an ocean-bottom-seismometer (OBS) experiment along G1 between January 2019 and February 2020, to determine the 3-D seismic velocity structure of the area and relocate the local earthquakes. Our velocity models reveal a large low-velocity anomaly extending through the entire oceanic crust along G1 with some along-strike variations. We identify a 10 km-long rupture barrier zone, which is interpreted to be highly fractured with enhanced fluid circulation. We further suggest that the observed deep seismicity underlying the rupture barrier zone may indicate sea-water infiltration. Lastly, we apply the same approach to the westernmost segment of the GTF and observe some similarities and differences between the two fault zone seismic velocity structures.
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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 | 0.000 |
| 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".