Evidence of the ambiguous critical state transition from aseismic to seismic slip
Bibliographic record
Abstract
<!--!introduction!--> The idea that earthquake processes occur on a continuum from aseismic (stable sliding) to seismic slip (event nucleation) is not new, however the mechanisms causing any evolution between the two end-members is not fully understood. Possible mechanisms may relate to dynamic fault weakening, static stress transfer, the concentration of shear stress at the boundary of an aseismic region, some combination of these, or a mechanism we have yet to detect. Moreover, the detection of aseismic processes is inherently difficult, adding to the challenges in detecting and understanding this evolution. Here, we investigate evidence for a critical state transition within the subsurface using data from several recent seismic sequences in western Canada. The first case investigates a potential change in seismic event rate following prolonged fluid injection at a water disposal well, suggesting that initial deformation in the subsurface related to the injection was aseismic. Twelve months into the injection program, a large change in the seismic event rate was observed, along with a change in the source characteristics of the events, suggesting a transition from dominantly aseismic to seismic slip. Another case investigates seismicity in a historically quiescent area where there is ongoing fluid injection. A M5.3 mainshock was followed by an unusual aftershock sequence, which showed limited evidence of Omori-like decay, and instead, remained persistent. We investigate these sequences using an array of techniques including ambient seismic noise, repeating seismicity and the identification of tremor-like signals to determine whether there is evidence of a critical state transition at depth.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".