Seismic attenuation in the interior of British Columbia and westernmost continental craton
Bibliographic record
Abstract
In this study we investigated coda-wave attenuation (QC) in the interior of British Columbia, with a focus on stations in the eastern Cordillera and westernmost continental craton using records from 13 stations (short period and broadband) of the Canadian National Seismic Network (CNSN). Our dataset is comprised of 1832 earthquakes recorded between 1992 and 2017 with magnitudes ranging from 1.5 to 4.9, depths from 0 to 54 km (with the vast majority being <15 km) and epicentral distances of 15 to 100 km. This gives a total of 1214 high signal-to-noise (S/N) traces (S/N?5.0) useful for QC calculation (with a range of ellipse parameter, a2, of 20 to 100) across the region. Coda windows were selected to start at tc = 2tS (two times the travel time of the direct S wave), and were filtered at center frequencies of 2, 4, 8, 12 and 16 Hz. Our study reveals a consistent pattern. We find that in the interior of BC, the lowest Q0 values (e.g., Q0 of 45) are at station BCBC at the western end of the Anahim Volcanic Belt. This is consistent with previous studies showing a low average Q0 of 53 (a2 of 30-50 km) for stations within that volcanic belt. The highest Q0 values that we find (e.g., Q0 of 165) are at station BLBC, located on the western edge of the continental craton. Other stations in the interior of BC show intermediate values of Q0. One surprising result is that FNBB and BMBC stations in northeast BC - also located on the western edge of the continental craton - show consistently low Q0 values (46-76 over the range of a2 from 20 to 70). Those stations were deployed in a region of hydraulic fracturing activity, and the low Q0 values may be partially attributed to fluids or fracturing in the uppermost crust.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".