A Further Source of Tokyo Earthquakes and Pacific Ocean Tsunamis
Bibliographic record
Abstract
Earthquake hazard assessments for the Tokyo Region are complicated by the trench–trench triple junction where the oceanic Philippine Sea Plate not only underthrusts a continental plate but is also being subducted by the Pacific Plate. Great thrust earthquakes and associated tsunamis are historically recognized hazards from the Continental/Philippine Sea (Sagami Trough) and Continental/Pacific (Japan Trench) plate boundaries but not from the Philippine Sea/Pacific (Izu–Bonin Trench) boundary alone. Here we employed a series of historical and hypothetical rupture models to explain the widespread distribution of geological evidence for an unusually large tsunami found along 50 km of coastline east of Tokyo. Dating to about 1,000 years ago, this inferred tsunami predates local written history by several hundred years. We found that the inland extent of its sand sheet is best explained, in computer simulations, by displacement on one of the three plate boundaries offshore of the Boso Peninsula, which corresponds to the triple junction. The minimum magnitude scenario capable of generating the inland extent of inundation involves displacement along the Philippine Sea/Pacific boundary megathrust. This plate-boundary fault adds another potential source for earthquakes in the Tokyo Region and tsunamis in the Pacific Ocean. The Philippine Sea/Pacific boundary megathrust is another possible source of seismic hazard in the Tokyo Region and tsunamis in the Pacific, according to an assessment of 1,000 years of tsunami deposits along the Japanese coastline.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".