Local site effects in Ottawa, Canada - first results from a strong motion network
Bibliographic record
Abstract
A five station strong motion network of ETNA instruments was established in Ottawa in the winter of 2002. The network was designed to sample typical site conditions across the urban area, and forms one prototype for the Canadian Urban Seismology Project, intended to gather weak motion data in the short-term, and produce near-realtime shake maps in the long-term. Sites were placed at the Ottawa Observatory and the Eco-Musee (rock), Glebe High School (<5 m soil), Westminster Avenue (10 m soil), and Fallingbrook (18 m soil). After careful attention to site noise characteristics, the trigger thresholds were set in the range 0.02 - 0.12 %g. Observatory recorded a magnitude 3 earthquake at 50 km distance in January 2002, and then all stations (less Eco-Musee which had flooded) recorded a Mw 5.0 event at 190 km in April 2002. Remarkably, two instruments recorded a Mw 3.7 aftershock. We have analyzed the 6 records for consistency and find significant amplification and sharp resonance peaks in the Fallingbrook site. Although strong ground motion records are of the greatest value, these weak motion records help to calibrate engineering models in the linear range of soil behavior. Some degree of extrapolation will probably be required to predict local effects for damaging strong motions.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".