Vs30 and Fundamental Site Period Estimates in Soft Sediments of the Ottawa Valley from Near-Surface Geophysical Measurements
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Abstract Seismic techniques have been used to supplement geological and geophysical borehole data for assessing earthquake hazard in the Ottawa Valley near Ottawa, Ontario, Canada. The methodology used to obtain critical parameters for site effect studies (depths of major contacts, shear-wave velocity-depth function) is presented in this paper. Bedrock depth values and basic stratigraphic information were obtained from water well descriptions and three geological units were defined: post-glacial marine, deltaic and fluvial sediments (mainly silt, clay and sand), glacial sediments (till, glaciofluvial sand and gravel), and Paleozoic (limestone, shale) and Precambrian bedrock. In order to augment existing knowledge of bedrock depths and overburden stratigraphy, 100 P-wave reflection soundings (test sites) were acquired. Good quality, high-frequency data have allowed identification of the reflections associated with the glacial-post-glacial boundary as well as the top of bedrock at each site. Subsequently, P-wave and S-wave velocities measured from high-resolution downhole logging in boreholes in the Ottawa Valley area have been used to establish P- and S-wave velocity-depth functions for each stratigraphic unit. We have used these results to: 1) obtain thickness of post-glacial and glacial sediments and bedrock depth at the P-wave reflection sites, 2) calculate Vs30 for all borehole and seismic test site locations and plot NEHRP site classifications over the study area, and 3) combine shear-wave velocity and depth/thickness information to obtain a fundamental resonance period map. We demonstrate that large lateral variations in Vs30, as well as resonance effects, occur within the project area, and that the Vs30 criterion used in NEHRP site classifications is sensitive to the presence and depth of a high-velocity contrast within 30 m of the ground surface. Using the 30-m criterion may not provide an adequate description of the site effects in this environment.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it