Seven years of postseismic deformation following the 1999, <i>M</i> = 7.4 and <i>M</i> = 7.2, Izmit‐Düzce, Turkey earthquake sequence
Bibliographic record
Abstract
We report the results of nearly 7 years of postseismic deformation measurements using continuously recorded and survey mode GPS observations for the 1999 Izmit‐Düzce earthquake sequence. Resolvable, time‐dependent postseismic changes to the preearthquake interseismic velocity field extend at least as far as the continuous GPS station in Ankara, ∼200 km southeast of the Izmit rupture. Seven years after the earthquake sequence, the relative postseismic velocity across the North Anatolian Fault (NAF) reaches ∼10–12 mm/a, roughly 50% of the steady state interseismic rate, with the highest postseismic velocities within 40 km of the coseismic ruptures. We use a sequence of logarithmic time functions to fit GPS site motions. Up to three logarithmic terms with decay constants of 1, 150, and 3500 days are necessary to fit all the transient motion observed at the continuous GPS stations. The first term is required for the component of site motion parallel to the NAF at near‐field sites strongly implicating rapid, shallow afterslip. The intermediate and longer‐term postseismic velocity components reflect more broadly distributed strain with a symmetric double‐couple pattern suggestive of either localized, deep afterslip or viscoelastic relaxation of the upper mantle and/or lower crust. In two areas (including the Marmara Sea) this pattern is superimposed on north‐south extension centered on the NAF. We speculate that this extension may result from aseismic dip slip along coseismically weakened faults, driven by the background tectonic stress.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".