Experimental Monitoring of Crack Closing and Sliding with Nonlinear Wave Interactions
Bibliographic record
Abstract
It is now well-established that earthquakes change the seismic velocity of the near surface. There is certainly some understanding of what mechanisms are responsible for these changes, but there remain many questions. Here we attempt to answer the question of the relative importance of different connection mechanisms between cracks and how these change with applied load. To study this, we first perform nonlinear wave-mixing experiments in two sandstone samples at a variety of applied uniaxial stresses. The two samples differ in the relative orientation of their microstructures. We find that although the samples show velocity anisotropy we do not see aligned structures in scanning electron microscope images. By measuring the changes in velocities with applied stress we find that most cracks close during our experiments independent of crack orientation. By contrast, we find that the nonlinear wave interactions vary strongly with applied load and with crack orientation. We analyze these differences and relate them to an emerging model of nonlinear wave interactions with microstructures.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".