Site Period Estimations Using Microtremor Measurements- Experimental and Analytical Studies in British Columbia
Bibliographic record
Abstract
This paper presents site period investigations at nodes on a 1-km grid within a 6-km by 8-km area in Vancouver and Richmond, BC. The area includes a range of site conditions, and is selected as the pilot application area for an urban seismic instrumentation project (Canadian Urban Seismology Program- CUSP) undertaken by the Geological Survey of Canada (GSC). The pilot project area is situated in one of the most seismically active regions in Canada and part of it lies on thick deltaic sediments that are known to have amplified ground motions during past earthquakes. Reliable site response models for the area are needed to quantify the amplification potential. Microtremor measurements provide a relatively inexpensive and simple tool to obtain one of the key parameters in site response studies, the site period. A series of microtremor measurements in the pilot CUSP area yielded site periods ranging from 0.05 seconds at bedrock outcrop to 4.2 seconds at some sites on the Fraser River delta in Richmond. Site periods were also estimated using a 1-D site-modeling program, SHAKE, for sites on the Fraser River delta. Each site was represented by a simplified 3-layer model with Holocene deposits, Pleistocene deposits and bedrock. The highest site period obtained from SHAKE modeling was 4.4 seconds about 3 km east of Richmond City Hall, for which the microtremor measurements indicated a site period of 4.2 seconds.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".