Predicting earthquake ground shaking due to 1D soil layering and 3D basin structure in SW British Columbia, Canada
Bibliographic record
Abstract
This thesis develops and explores two methodologies to assess earthquake ground shaking in southwestern British Columbia based on 1D soil layering and 3D basin structure. To assess site response based on soil layering, microtremor array measurements were conducted at two sites of contrasting geology to estimate Rayleigh-wave dispersion curves. A Bayesian inversion algorithm is developed to invert the dispersion data for the shear-wave velocity (VS) profile together with quantitative uncertainty estimates, accounting rigorously for data error covariance and model parameterization selection. The recovered VS profiles are assessed for reliability by comparison with invasive VS measurements at each site with excellent agreement. Probabilistic site response analysis is conducted based on a sample of VS profiles drawn from the posterior probability density of the microtremor inversion. The quantitative uncertainty analysis shows that the rapid and inexpensive microtremor array method provides sufficient resolution of soil layering for practical characterization of earthquake ground motion. To assess the effects of 3D Georgia basin structure on long-period (> 2 s) ground motion for large scenario earthquakes, numerical 3D finite difference modelling of viscoelastic wave propagation is applied. Both deep (> 40 km) subducting Juan de Fuca plate and crustal (5 km) North America plate earthquakes are simulated in locations congruent with known seismicity. Simulations are calibrated by comparing synthetic waveforms with 36 selected strong- and weak-motion seismograms of the 2001 MW 6.8 Nisqually earthquake. The ratio between predicted peak ground motions in models with and without Georgia basin sediments is applied as a quantitative measure of basin amplification. Steep edges in the upper 1 km of the northwest and southeast extents of the basin are coincident with the appearance of surface waves. Focussing of north-to-northeast propagating surface waves by shallow (< 1 km) basin structure increases ground motion in a localized region of southern Greater Vancouver. This effect occurs for both types of earthquakes located south-southwest of Vancouver at distances greater than ~80 km. The predicted shaking level is increased up to 17 times and the duration of moderate shaking (> 3.4 cm/s) is up to 16 times longer due to the 3D Georgia basin structure.
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.
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".