Mapping Disturbed Ground Using Compressional and Shear Wave Reflection Sections
Bibliographic record
Abstract
At some sites near Ottawa, Ontario, thick glaciomarine sediments deposited in the Champlain Sea after the final retreat of the Winsconsinan icesheet ∼11,000 years ago show evidence of severe “disturbance” by ground motions during a prehistoric earthquake(s). The Geological Survey of Canada has been investigating these areas to better understand seismic site response and paleoseismicity. This paper presents results obtained with 3-component seismic reflection surveys over such disturbed terrains. Shallow seismic reflection surveys are used to provide subsurface architectural and stratigraphic information. In Champlain Sea sediments, high-resolution compressional (P-) and shear (S-) wave reflection sections have been obtained using a vibratory source/landstreamer data acquisition system. Where the large-scale depositional structure of the fine-grained marine sediments has been disrupted and/or liquefied, the shear wave reflection data quality can be highly compromised. This is interpreted to indicate that the disturbed ground is scattering shear wave energy at the wavelength scale (∼ 1 metre). In contrast, P-wave sections are not degraded in quality to the same extent since the signal wavelengths are longer and the velocity is strongly influenced by interstitial porewater. Comparison of compressional and shear wave data from areas of disturbed ground can provide information on the thickness of the soft fine-grained glaciomarine sediments and the underlying bedrock topography, as well as give new insights into the properties of the disturbed sediments. Such information can lead to better hazard and risk assessments throughout the Ottawa Valley-St. Lawrence Lowlands region of eastern Canada where similar glaciomarine deposits are found.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 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".