Calculation of the Focal Mechanism for Composite Microseismic Events
Bibliographic record
Abstract
Summary It is generally difficult to obtain a reliable single-event source mechanism with a sparse surface array, mainly due to the typically low signal/noise ratio and poor azimuthal coverage. In this study, we propose an inversion procedure to estimate the focal mechanism of composite microseismic events - i.e., a set of events interpreted to share a common focal mechanism - recorded using a sparse surface network. Our method uses polarities of P-wave first motion together with Sh/P amplitude ratios. Sensitivity analysis using synthetic data indicates that reliable focal solutions can be obtained if both the amplification factor on Sh/P ratio is within the range of 0.25 ∼ 1.0, and > 50% polarities are correctly picked. We apply our approach to a set of 13 microseismic events recorded during hydraulic-fracture stimulation of the Marcellus Shale formation in West Virginia and Pennsylvania, USA. Similar to previous studies of this area, we obtain a focal mechanism comprised of northwest or northeast trending strike-slip faulting accompanied by a minor thrust-faulting component.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".