Natural and Induced Seismicity in the Lake Erie-Lake Ontario Region: Reactivation of Ancient Faults with Little Neotectonic Displacement
Bibliographic record
Abstract
The two most prominent seismic zones in the Lake Erie-Lake Ontario region are associated with the Akron magnetic lineament and with the Clarendon-Linden fault. Both these features are recognized from geophysical data as regional basement structures related to the Grenville collisional orogen. Neotectonic displacement is not geologically evident, although Paleozoic reactivation is manifested by the Clarendon-Linden fault. We have sharpened the definition of seismic zones in the region by introducing newly discovered events, improving constraints on locations and size for many others, and omitting unreliable ones. This seismicity tends to occur on old faults with minor neotectonic displacements. Related conclusions are: 1) neotectonic surface displacement is not necessary for fault capability, 2) seismogenic faults may have geological and/or geophysical expressions, and 3) a stationary moment release at the historic level requires more capable faults than the ones active during the historic period. Waste fluid injection, oil recovery, and salt-brine recovery have been implicated in cases of induced seismicity in the study area and might have contributed a significant portion of the known earthquakes. Fluid is being injected into the basal platform formation at a depth of 1.8 km near Ashtabula, Ohio. In July 1987, about a year after the onset of injection, a mbLg=3.8 main shock occurred within a 60 km wide area with no known prior seismicity. Aftershocks detected by a short-term local seismic network define a vertical left-lateral fault in the basement just below the platform rocks as close as 700 m from the injection well, probably a reactivated pre-existing fault. Subsequent seismicity suggests a westward migration by 5-10 km, possibly along the same fault.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".