Tectonic tremor: The chatter of mafic underplating
Bibliographic record
Abstract
Tremor is a weak seismic signal accompanying slow fault slip at plate boundaries. The relationship between tremor and slow slip and the tremor source mechanism have been widely debated, owing largely to the challenge of accurately locating tremor in depth. We assemble a tremor hypocenter catalog of 4,851 events in a 10 x 20 km2 area beneath Vancouver Island during three slow slip episodes between 2003 and 2005 using a cross-station detection method adapted from previous studies to recover accurate depths. Improved tremor locations provide key constraints on i) thickness of the tremorgenic zone, ii) the relative location of tremor to key structural features in the subduction complex, and iii) the geologic context and mechanism of tremor. Tremor occurs in quasi-planar clusters < 500 m thick at a depth near 39 km, beneath a high reflectivity layer and within a zone of elevated Poisson's ratio with P-wave velocities of ~7 km/s. We interpret tremor as originating in the fragmentation of the upper few hundred meters of basaltic oceanic crust. Comminuted and overpressured basalt with increasingly anisotropic fabric is underplated onto overriding lithosphere to generate high reflectivity. Tremor thus manifests areas of material transfer across the plate boundary during slow slip.
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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 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".