Spherical‐Earth finite element model of short‐term postseismic deformation following the 2004 Sumatra earthquake
Bibliographic record
Abstract
Decadal‐scale postseismic deformation of subduction earthquakes has been widely modeled using a Maxwell viscoelastic Earth with a mantle‐wedge viscosity of about 10 19 Pa s. Short‐term postseismic deformation within a few years after the earthquake remains a more challenging problem because of the predominance of afterslip of the megathrust and the potentially more complex mantle rheology. Questions include the necessity of invoking the transient rheology and the relative importance of contributions from afterslip and viscoelastic relaxation. In this work, we address these questions by developing a spherical‐Earth viscoelastic finite element model for the short‐term postseismic deformation following the magnitude 9.2 Sumatra earthquake of 2004. The model consists of elastic overriding and subducting plates and a viscoelastic mantle of bi‐viscous Burgers rheology, with the continental mantle (mantle wedge) being less viscous than the oceanic mantle by a factor of ten. Primary observational constraints for the short‐term postseismic deformation include ∼1 year net displacements of nine near‐field GPS sites and ∼3 year time series from three far‐field sites several hundred kilometers from the 2004 rupture zone. Model results indicate that the afterslip of the fault must be at work within the first few years after the earthquake. The observed deformation is best explained with a model that includes both the afterslip and transient rheology. In the preferred model, the transient and steady state viscosities of the mantle wedge are 5 × 10 17 Pa s and 10 19 Pa s, respectively.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".