III II II I EASTERN SECT IONi SEISMOLOGICAL Linking Historical Intensity Observations with Ground-motion Relations for Eastern North America
Bibliographic record
Abstract
Modified Mercalli Intensity (MMI) data are the only avail-able ground-motion data for most of the large historical earthquakes that have occurred in eastern North America (ENA). Are these historical observations consistent with expected intensity levels based on regional ground-motion relations? It is important to answer this question, as it bears on the reliability of the results of seismic hazard analyses. An empirical study of California strong-motion records and associated MMI values has shown that observed MMI is a function of response spectral amplitudes, magnitude, and distance (Atkinson and Sonley, 2000). Comparison of strong-motion and MMI data from the 1988 Saguenay, QuEbec, earthquake confirms applicability of the California relations to ENA, at least for epicentral distances of 150 km or less. I therefore apply the relationships of Atkinson and Sonley (2000) to predict the MMI for historical ENA earth-quakes as a function of distance, assuming that the response spectral amplitudes follow those of the ENA ground-motion relations of Atkinson and Boore (1995). The ground motions are adjusted to show the expected MMI for a range of soil conditions, including hard rock, firm ground, and soft soil. The predicted MMI values for firm-ground to soft-soil conditions are consistent with historical observations from most ENA earthquakes, with typical discrepancies r present-ing overprediction or underprediction of observations by about 1 MMI unit. Specifically, observed intensities from the 1886 Charleston earthquake (M 7.3) and the 1925 Charlevoix earthquake (M 6.4) are weaker than predicted by about one intensity unit, while observed intensities from the 1811-1812 New Madrid earthquakes (M 8) are larger than predicted by about one unit. Intensities from the 1968 Illi-nois earthquake (M 5.4) and the 1988 Saguenay earthquake (M 5.8) are larger than predicted by about 1.5 intensity units. On the whole, it is concluded that the historical MMI data are consistent with currently used ENA ground-motion relationships.
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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 | 0.001 | 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".