Estimating the Geoelectric Field and Electric Power Transmission Line Voltage During a Geomagnetic Storm in Alberta, Canada Using Measured Magnetotelluric Impedance Data: The Influence of Three‐Dimensional Electrical Structures in the Lithosphere
Bibliographic record
Abstract
Abstract Estimating the effect of geomagnetic disturbances on power grid infrastructure is an important problem since they can induce damaging currents in electric power transmission lines. In this study, an array of magnetotelluric (MT) impedance measurements in Alberta and southeastern British Columbia are used to estimate the geoelectric field resulting from a magnetic storm on September 8, 2017. The resulting geoelectric field is compared to the geoelectric field modeled using the more common method that uses a piecewise‐continuous 1‐D conductivity model. The 1‐D model assumes horizontal layers, which result in orthogonal induced electric fields while the measured MT impedance data can account for fully 3‐D conductivity structure. The geoelectric field derived from measured MT impedance data is partially polarized in southern Alberta, and the geoelectric field magnitude is largest in northeastern Alberta where the resistive Canadian Shield outcrops. The induced voltage in the Alberta transmission network is estimated to be ∼120 V larger in northeastern Alberta when using the measured MT impedances compared to the piecewise‐continuous 1‐D model. Estimated voltages on transmission lines oriented NW‐SE in southern Alberta are 10%–20% larger when using the MT impedances due to the polarized geoelectric field. As shown with forward modeling tests, the polarization is due to a feature in the lower crust (20–30 km depth) called the Southern Alberta British Columbia conductor that is associated with a Proterozoic tectonic suture zone. This forms an important link between ancient tectonic processes and modern‐day geoelectric hazards that cannot be modeled with a 1‐D analysis.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".