Surface Rupture Morphology and Vertical Slip Distribution of the 1959<b><i>M</i></b><sub><b><i>w</i></b></sub>7.2 Hebgen Lake (Montana) Earthquake From Airborne Lidar Topography
Bibliographic record
Abstract
Abstract The 1959Mw∼7.2 Hebgen Lake earthquake is among the largest continental normal faulting events recorded, as well as one of the earliest associated with a multifault rupture. Multimeter vertical slip was observed on three main, morphologically distinct strands: the Hebgen fault and southeastern section of the Red Canyon fault, which both follow sharp topographic rangefronts, and the Red Canyon fault Kirkwood Ridge section, which cuts steep topography in the footwall of the Hebgen fault. We augment early field, seismological, and geodetic studies by investigating the modern surface rupture using newly acquired airborne lidar topography. By estimating throw from scarp profiling of the ∼36.5 km primary surface rupture, we show both that peak 1959 slip occurred at a structurally mature part of the fault and that many 1959 slip minima are associated with clear structural complexities. Vertical slip often substantially exceeds throw measured at the fault free face immediately after the earthquake; the scarps do not conclusively express beveled forms characteristic of repeated slip and degredation, yet must in places capture both the 1959 earthquake (for which we estimate an average throw of 2.64 m) and one or two preceding latest Pleistocene–Holocene events known from trenching. This has wider, cautionary implications for interpreting paleo‐earthquake chronologies and deriving magnitudes from morphologically simple scarps. By comparing 1959‐only and multievent vertical displacement populations, and considering preliminary paleoseismic data, we suggest that large surface‐rupturing earthquakes on the Hebgen and Red Canyon faults involve highly variable slip distributions.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".