Multiscale postseismic behavior on a megathrust: The 2012 Nicoya earthquake, Costa Rica
Bibliographic record
Abstract
Abstract The Nicoya Peninsula in northwest Costa Rica overlies a section of the subduction megathrust along the Middle America Trench. On 5 September 2012, a moment magnitude 7.6 megathrust earthquake occurred beneath a dense network of continuous GPS and seismic stations. Many of the GPS stations recorded the event at high rate, 1 Hz or better. We analyze the temporal and spatial evolution of surface deformation after the earthquake. Our results show that the main rupture was followed by significant afterslip within the first 3 h following the main event. The behavior of the surface displacement can be represented by relaxation processes with three characteristic times: 7, 70, and more than 400 days. We assume that the long relaxation time corresponds to viscoelastic relaxation and the intermediate relaxation time corresponds to afterslip on the main fault. The short relaxation time may represent a combination of rapid afterslip, poroelastic adjustment in the upper crust, or other processes. During the first few months that followed the earthquake, afterslip likely released a significant amount of slip deficit still present following the coseismic rupture, in particular updip of the rupture. Afterslip seems to be bounded updip by regions affected by slow slip events prior to the earthquake, suggesting that the two processes are influenced by different frictional properties.
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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 | 0.000 |
| 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".