Further evidence for the compound nature of slow earthquakes: The Prince Edward Island earthquake of April 28, 1997
Bibliographic record
Abstract
Seismograms of the April 28, 1997, Prince Edward island transform fault earthquake (Mw 6.8) show clear evidence for the superposition of two types of rupture, a normal earthquake and a slow component which primarily radiated energy at low frequencies. We combined low‐frequency spectral data with P waveform data to invert for a source time function that satisfied data from 0.001 to 2.5 Hz. The results show that the earthquake started with a slow event which began ∼15 s before the fast mainshock and was part of a slow earthquake which lasted over 30 s. The smoothness of the initial event is inferred from the low amplitude of high‐frequency energy at regional stations during the initial portion of the P wave arrival. Directivity analysis shows that the two components of the rupture occurred on different faults. The slow event occurred on the main transform, and the fast event occurred on a parallel fault 40 km to the east. A similar compound sequence, involving both slow and fast components and rupture on multiple faults, occurred on the Romanche transform in 1994. These and other results for slow earthquakes suggest that many large events on oceanic transform faults are compound events.
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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 | 0.002 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".