The wedge model revisited: A physical modeling experiment
Bibliographic record
Abstract
Abstract To assess seismic amplitude effects commonly associated with the classic wedge model in geophysics, we built a scaled physical model of a simple high-velocity wedge immersed in water. In addition to demonstrating the well-known tuning effect related to thin beds, a 2D marine zero-offset seismic survey over the physical model shows a surprising number of high-amplitude dipping events corresponding to elastic multimodes, multiples, and mixed-mode reflections having nonreciprocal raypaths. These events cause additional complexities in the amplitudes of the top-wedge and base-wedge reflections that are not observed in simple acoustic seismic responses of the wedge model. Finite-difference, acoustic, exploding-reflector numerical model data, calculated using the same wedge geometry and velocity model, assisted in the identification of these events. It was found that the amplitudes of mixed-mode multiples in data recorded over high-velocity rocks with a wedge-like geometry might be significant. We also discovered that there is a maximum number of zero-offset pure-mode multiples within the wedge for a given wedge taper angle. Conventional P-wave migration of the physical model data confirmed that the multimode reflections degrade the quality of the migrated image.
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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 | 0.002 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| 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".