<i>In situ</i>evidence for frequency dependence of near-surface<i>Q</i>
Bibliographic record
Abstract
The frequency dependence of the quality factor Q has long been predicted by mathematical modelling and laboratory measurements; however, in situ evidence from seismic surveys is still lacking. We have conducted the cross-hole seismic surveys to investigate the near-surface seismic attenuation in the Daqing oilfield in northeastern China. The seismic waves were fired in a source hole of 40 m from the bottom to the surface at an interval of 1 m and were recorded in a receiver hole of 40 m by two geophones with one at the surface and the other one at the bottom. The direct waves were extracted to avoid the noise disturbance and the reflection interference, and the attenuations without the effects of the source signature and the receiver coupling were estimated by a method we proposed. The nonlinear attenuations were observed and fitted using the power-law-based Q. The reliability of Q estimate was verified by the high similarity between the real and the simulated attenuations. Therefore, the experiment we have conducted can be treated as a reliable evidence for the frequency dependence of near-surface Q.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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 | 0.000 |
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".