UPPER CRUSTAL STRUCTURE OF THE BELLINGHAM BASIN FROM GRAVITY AND AEROMAGNETIC DATA
Bibliographic record
Abstract
This study is aimed at identifying potentially active faults and deformation within the Bellingham basin in northwestern Washington. The basin is one of a number of forearc basins formed by the migration and rotation of tectonic crustal blocks in the upper plate of the Cascadia subduction zone. We have used gravity and aeromagnetic data from the U.S. Geological survey and other sources, along with our own data, to create anomaly maps and a 2.5D model of the upper crust. The model profile extends a length of more than 30 km from the Canadian border, southwest through the Bellingham basin to Lummi Island. The gravity data along the profile exhibit two highs on either end that straddle a gravity low in the central part of the basin. The magnetic data are characterized by three anomalies of high values, separated by moderately high values in the western section of the study area. The profile also crosses the projection into the basin of two crustal faults mapped along the western shoreline. The model along the profile is constrained by geologic data, LiDAR data, and well-log information, although these data are limited. We use a combination of wavelength-separation methods and forward modeling to construct interpretations of the subsurface structure. Two northwest-southeast-trending faults, the Birch Bay and Drayton Harbor faults, appear as distinct lineations caused by high gradients in vertical derivative grids calculated from the total field magnetic anomaly. These lineations project into the basin and correspond to offsets in layers included the cross-sectional model. The best-fit gravity model shows the Birch Bay fault cutting through a south-verging anticlinal structure (northeast side up). The Drayton Harbor fault, however, is not clearly expressed in the subsurface gravity model, but forms a prominent lineation in the magnetic data.
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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 | 0.001 |
| 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 | 0.001 |
| 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".