An overview of seismic attenuation in the western Quebec seismic zone
Bibliographic record
Abstract
We investigate seismic attenuation characteristics of the Western Quebec Seismic Zone. This zone constitutes a vast territory that encloses the Ottawa Valley from Montreal to Temiscaming, as well as the Laurentians and Eastern Ontario. We used earthquake recordings from 23 seismograph stations of the Canadian National Seismic Network (CNSN) across the region. Our dataset is comprised of 1887 earthquakes recorded between 1985 and 2022 with magnitudes ranging from 2.0 to 5.2, depths from 0 to 28 km and epicentral distances of 5 to 100 km. This gives a total of 1207 high signal-tonoise (S/N) traces (S/N≥5.0) useful for QC calculation (with a maximum ellipse parameter, a2, of 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 the highest Q0 (Q at 1 Hz) values are at station DPQ (e.g., Q0 of 124). The lowest Q0 values that we find are at the station GAC (e.g., Q0 of 60) that is the closest station (D=20 km) to the epicenter of the 2010 Val des Bois earthquake (MW 5.0) and located 67 km from the 2013 Ladysmith earthquake (MW 4.6). Also, we find the lowest overall average Q0 values at station GAC (e.g., Q0 of 74). We determined temporal variations in attenuation following the 2010 earthquake. The overall average of Q0 decreased from 77 (before the mainshock) to 69 (GAC, D=20 km), from 80 to 77 (OTT, D=57 km) and from 96 to 84 (WBO, D=99 km). These results are in agreement with global studies that show a decrease in Q0 following a major earthquake, likely the result of increased fracturing and fluids in the epicentral region. An average for all the data results in a Q relationship of QC = 83f1.07 for the frequency band of 2 to 16 Hz for the entire region.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.009 | 0.017 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.018 | 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".