Double-difference earthquake relocation of Charlevoix seismicity, Eastern Canada and implication for regional geological structures
Bibliographic record
Abstract
Eastern Canada is located within the North American Plate and, therefore, should have a relatively low rate of earthquake activity compared with interplate boundary. However, large earthquakes do occur in the region, especially in the Charlevoix Seismic Zone (CSZ) located about 100km downstream from Quebec City. In history, the Charlevoix Seismic Zone has been subject to five earthquakes with magnitude 6 or larger (M~7 in 1663; M~6 in 1791 and 1860; M~6.5 in 1870; MS 6.2 +_0.3 in 1925). However, the regional geological structures of the CSZ are not well understood. As one of the most seismically active region in Eastern Canada, the earthquakes in the CSZ are a significant hazard. Therefore, improved knowledge of distribution and seismic characteristics of these events provides a great benefit for understanding the seismic hazard of the CSZ. In this thesis, I apply earthquake location technique on discovering fault features in CSZ. Earthquake location, as a basic technique in seismometry, plays an important role in the studying of fault structures. The double-difference earthquake location algorithm (HYPODD) is able to get high-resolution hypocenter locations by introducing the residual between observed and calculated travel times between two events, and removing the effects of the un-modeled velocity structure. In this thesis, the resolution of double-difference location algorithm was analyzed using the seismic data of Canadian National Seismograph Network(CNSN) from Jan,1988 to Oct, 2010. The double-difference earthquake location algorithm was used to relocate more than 400 earthquakes in the Charlevoix seismic zone (CSZ), using a layered velocity model. The location results of initial catalog data and double-difference relocation results visually compare with each other, and the cross section of the northeast part in CSZ shows two nearly parallel faults dipping about 60 degree to the southeast. This provides evidence that there are minor rifting geological features underneath the St-Laurence River.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".