A Review Study of the Source Parameters of the 23 August 2011 Mw 5.7 Virginia Earthquake
Bibliographic record
Abstract
Abstract The source parameters of the 23 August 2011 M w 5.7 Virginia earthquake have been further studied. To perform our source parameter review study, we first retrieved waveform records from Incorporated Research Institutions for Seismology. We then carefully selected 17 stations that had good Rayleigh‐wave records. We used these 17 vertical records to retrieve a crustal shear‐wave velocity model surrounding the epicenter. Using the regional depth phase modeling method, we retrieved focal depths for the mainshock and seven larger aftershocks, which ranged from about 3 to 10 km. With the retrieved focal depths, the arrival times of the P and S phases at four close stations and a revised hypoDD program package, we relocated the mainshock and seven larger aftershocks. On the vertical profile with an azimuth of 119°, the hypocenter trend was at 52° down from horizontal. The moment tensor of the mainshock was inverted by modeling long‐period Rayleigh‐wave records at 11 stations selected with consideration of a balanced distribution around the epicenter. Combined with the hypocenter trend, a plane solution with a strike of 29°, a dip of 55°, and a slip of 113° was identified to be close to the real rupture plane of the mainshock. The rupture process of the mainshock was preliminarily analyzed using regional waveform records. At least four subevent ruptures were found. The initiate depth of the first subevent rupture was at about 7.8 km, and the rupture speed was at about 1.3 km/s. The time gap between subevent ruptures 1 and 2 was about 0.34 s.
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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 | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.009 | 0.006 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 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".