Evaluation and Updates for the USGS San Francisco Bay Region 3D Seismic Velocity Model in the East and North Bay Portions
Bibliographic record
Abstract
ABSTRACT We update the eastern and the northern portions of the detailed domain of the U.S. Geological Survey San Francisco Bay region 3D seismic velocity model (SFVM) based on comparisons of recorded and synthetic ground motions from 20 moderate (Mw 3.7–4.6) earthquakes. We modify the current SFVM (v.08.3.0) by assigning alternate property-versus-depth relations to the existing 3D geologic model. In some places, changes correspond to reassigning correct relations in which geologic units appear to be mislabeled, and in other places we subdivide geologic units where mapped geologic boundaries are missing from the 3D models so that we can implement a velocity contrast across a boundary. We also make ad hoc adjustments to velocity rules near the surface in some areas to better fit arrival times (specifically, in the Livermore basin). The updates reduce misfits in waveform correlation, travel time, cumulative absolute displacement, and peak ground velocity and are included in v.21.1 of the model. The selected earthquakes are small enough so that we neglect finite-source effects and model them as point sources. This allows us to assume that observed waveform characteristics are the result of path effects, and discrepancies between synthetic and recorded motions arise from misrepresentation of the elastic properties. Our analysis suggests refining the 3D geologic model, and adjusting the rules assigning properties to the geologic units will further improve the accuracy of the SFVM for simulating earthquake ground motions.
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How this classification was reachedexpand
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 | 0.001 | 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 | 0.001 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".