PALEOSEISMIC SURF AND TURF: UPDATES FROM THE USGS POWELL CENTER CASCADIA EARTHQUAKE WORKING GROUP ON SYSTEMATIC INTEGRATION OF ONSHORE AND OFFSHORE RECORDS AND FUTURE DIRECTIONS
Bibliographic record
Abstract
The lack of historic seismicity along the Cascadia subduction zone (CSZ) fuels the uncertainty of the megathrust rupture process and resulting hazards in the US and Canadian Pacific Northwest. Diverse types of paleoseismic proxies uniquely record different aspects of the earthquake rupture process. Thus, margin-wide integration of paleoseismic proxy records leverages these unique transcripts to provide a richer understanding of past earthquake variability in time and space. In a series of virtual workshops, the USGS Powell Center research group on CSZ earthquake science and hazards have compiled paleoseismic records of coseismic coastal land-level change, tsunami inundation, and ground shaking proxies such as landslides, liquefaction, and turbidites. To consistently integrate different datasets, we constructed ranking schemes to quasi-quantitatively evaluate the quality of geochronologic age control and certainty of earthquake evidence at 49 coastal land level change sites, 81 tsunami sites, 76 terrestrial paleoseismic shaking sites, and 13 marine paleoseismic shaking sites. At each site, we evaluated how well geochronologic samples and results (14C dates, stratigraphy, geological context etc.) constrain the timing of candidate earthquake events. Similarly, we applied an evidence quality ranking scheme to assess how certain the observations of coastal land-level change, tsunami inundation, and strong ground motion were the result of a CSZ megathrust earthquake source. We also focused on historic records of non-local events, such as the 1964 Alaska earthquake and the 1992 Cape Mendocino earthquake, to identify the characteristics of distal subduction zone earthquakes and small local events, respectively, in the paleoseismic record. In the future we plan to identify the likely rupture characteristics of major CSZ earthquakes during the Holocene and to synthesize paleoseismic, geophysical, and instrumental datasets to identify the existence and persistence of rupture boundaries along the subduction zone.
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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 | 0.005 | 0.015 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.012 | 0.012 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 0.005 |
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".