Magnetic distortion of the magnetotelluric tensor: a numerical study
Bibliographic record
Abstract
Decomposition of the magnetotelluric (MT) tensor when the electric field alone is subject to local galvanic distortion has received much attention in recent years. Recently some authors have extended such procedures to include the effects of the associated magnetic field distortion as well. With the aid of a three-dimensional modelling program the validity of the assumptions made in these analyses have been examined by considering the response over a range of periods of a small conductive cube at the surface of the earth and near a two-dimensional fault. The study indicates that the inclusion of magnetic distortion is necessary and important at short periods when induction occurs in the anomaly itself, but that the elements defining the magnetic distortion matrix become complex at such periods so that the assumptions underlying the theory are no longer valid. At longer periods the magnetic distortion matrix does become real and frequency-independent and therefore determinate, but its effect on the response becomes insignificant compared with that due to electric distortion. At these longer periods the phases of the regional impedances and the ratios of the electric distortion parameters are correctly recovered whether magnetic distortion is present or not. Calculations were repeated for a resistive cube, and also for a highly resistive region beneath the surface layer, with no significant enhancement of magnetic distortion. It is concluded that, at least for such models, inclusion of magnetic distortion in decompositions of the MT tensor does not, in general, offer any improvement over the conventional decompositions in which only distortion of the electric field is taken into account.
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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 | 0.000 | 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 | 0.000 |
| 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 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".