Crustal Deformation in Southern California Constrained by Radial Anisotropy From Ambient Noise Adjoint Tomography
Bibliographic record
Abstract
Abstract We build a new radially anisotropic shear wave velocity model of Southern California based on ambient noise adjoint tomography to investigate crustal deformation associated with Cenozoic evolution of the Pacific‐North American plate boundary. Pervasive positive radial anisotropy (4%) is observed in the crust east of the San Andreas Fault (SAF), attributed to subhorizontal alignment of mica/amphibole foliation planes resulting from significant crustal extension. Substantial negative anisotropy (6%) is revealed in the middle/lower crust west of the SAF, where high shear wave speeds are also observed. The negative anisotropy could result from steeply dipping amphibole schists in a shear zone developed during Laramide flat slab subduction. Alternatively, it could be caused by the crystal preferred orientation (CPO) of plagioclase, whose fast axis aligns orthogonally to a presumed subhorizontal foliation. The latter new mechanism highlights potentially complex CPO patterns resulting from different lithospheric mineralogy, as suggested by laboratory experiments on xenoliths from the region.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.001 | 0.002 |
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; both teacher heads agree on what is shown here.
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".