An Integrated Stratigraphic Approach to Investigating Evidence of Paleoearthquakes in Lake Deposits of Eastern Canada
Bibliographic record
Abstract
Seismic shaking can generate mass movements, turbidites, and soft-sediment deformation within lake basins. These ‘disturbed’ deposits may be preserved, and provide a stratigraphic record of paleoearthquakes. A three-dimensional seismo-stratigraphy of the lake deposits can be constructed from a high-density, sub-bottom acoustic profile (SAP) survey, allowing disturbed deposits within the basin to be identified and mapped. Event layers composed of one or more disturbed deposits can be identified within the seismo-stratigraphy, and targeted coring of the lake deposits provides ground-truthing of the disturbed deposits. Analysis of organic or sediment materials sampled from recovered cores allow ages to be assigned to the event layers. Maps depicting the distribution, extent and types of disturbed deposits within each event layer can be compiled by integrating the event layer stratigraphy and the three-dimensional architecture of the lake deposits. An intrabasin, multi-deposit event layer is the likely signature of significant past earthquake shaking, but possible non-seismic triggers also need to be assessed. An earthquake catalogue spanning 16 000 years for central Switzerland exemplifies the results of an integrated seismo- and chrono-stratigraphic approach to paleoseismic investigation. This approach to the investigation of eastern Canadian lake basin(s) has the potential to significantly augment the eastern Canadian earthquake catalogue. Conversely, the absence of seismically-induced disturbed deposits in SAP profiles and in lake core within a given area can help establish negative evidence of paleoseismicity.RÉSUMÉLes secousses sismiques peuvent provoquer des mouvements de terrain, des turbidites, ainsi que la déformation de sédiments meubles dans les bassins lacustres. Ces dépôts « perturbés » lorsque préservés constituent des archives stratigraphiques de ces paléoséismes. Une sismostratigraphie tridimensionnelle des dépôts lacustres peut être élaborée par sondage acoustique haute densité de sédiment (SAP), permettant ainsi de détecter et de cartographier les dépôts perturbés du bassin. Les couches événementielles composées d'un dépôt perturbé ou plus peuvent être détectées par sismostratigraphie, et le carottage ciblé de dépôts lacustres permet de les valider. L’analyse de matériaux organiques ou de sédiments prélevés à partir des carottes permettent de dater les couches événementielles. Des cartes illustrant la distribution, l'étendue et les types de dépôts perturbés au sein de chaque couche événementielle peuvent être compilées en intégrant la stratigraphie de la couche événementielle et l'architecture tridimensionnelle des dépôts lacustres. Une couche événementielle multi-dépôt est la signature probable d’importants tremblements sismiques anciens, sans perdre de vue que d’autres déclencheurs non sismiques puissent être en cause. Un catalogue de séismes couvrant 16 000 ans d’événements dans le centre de la Suisse illustre les résultats d'une approche sismologique et chrono-stratigraphique intégrée de l’histoire paléosismique. Cette approche d’étude de bassins lacustres de l'Est canadien permet d'augmenter considérablement le nombre de séismes du catalogue de l'Est canadien. Inversement, l'absence de dépôts perturbés induits par séisme dans les profils SAP et dans des carottages d’une zone donnée peut contribuer à constituer une preuve de l’absence de paléosismicité.
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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 | 0.006 | 0.008 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".