Least squares inversion of one-dimensional magnetotelluric data: An assessment of procedures employed by Brown University

1986 ◽  
Vol 8 (2) ◽  
pp. 187-231 ◽  
Author(s):  
Jens Pedersen ◽  
John F. Hermance
Keyword(s):  
Least Squares ◽  
Magnetotelluric Data ◽  
One Dimensional ◽  
Brown University

scholarly journals Sediment compaction and magnetotelluric data in the Eromanga Basin

1989 ◽  
Vol 20 (2) ◽  
pp. 335
Author(s):  
J.P. Cull ◽  
J.D. Gray
Keyword(s):  
Fine Structure ◽  
Least Squares ◽  
Geological Mapping ◽  
Magnetotelluric Data ◽  
One Dimensional ◽  
Sediment Compaction ◽  
Non Linear ◽  
Statistical Justification ◽  
Geological Constraints ◽  
Eromanga Basin

Magnetotelluric data obtained in the Eromanga Basin can be interpreted using one-dimensional models to describe plane layers consistent with geological mapping. Interpretations are based on the results of non-linear inversions generating a minimum least-squares error between the observations and the model. However there is no statistical justification for selecting highly complex starting models. In particular adequate solutions can be generated using models based on 2, 3 or 4 layers over basement; additional layers defining fine structure can only be retained using external geological constraints. Solutions based on random starting models suggest gradations in resistivity (1?4 ohm m) consistent with sediment compaction. Major discontinuities in all models (4?30 ohm m) are assumed to indicate a basement contact at depths of 7?8 km.

scholarly journals One-dimensional constrained inversion study of TEM and application in coal goafs’ detection

2020 ◽  
Vol 12 (1) ◽  
pp. 1533-1540
Author(s):  
Si Yuanlei ◽  
Li Maofei ◽  
Liu Yaoning ◽  
Guo Weihong
Keyword(s):  
Least Squares ◽  
Least Squares Method ◽  
Data Interpretation ◽  
Volume Effect ◽  
Underground Space ◽  
Attenuation Curve ◽  
One Dimensional ◽  
Transient Electromagnetic ◽  
Geological Conditions ◽  
Geological Information

AbstractTransient electromagnetic method (TEM) is often used in urban underground space exploration and field geological resource detection. Inversion is the most important step in data interpretation. Because of the volume effect of the TEM, the inversion results are usually multi-solvable. To reduce the multi-solvability of inversion, the constrained inversion of TEM has been studied using the least squares method. The inversion trials were performed using two three-layer theoretical geological models and one four-layer theoretical geological model. The results show that one-dimensional least squares constrained inversion is faster and more effective than unconstrained inversion. The induced electromotive force attenuation curves of the inversion model indicate that the same attenuation curve may be used for different geological conditions. Therefore, constrained inversion using known geological information can more accurately reflect the underground geological information.

A STUDY OF HIGHER-ORDER DISCONTINUOUS GALERKIN AND QUADRATIC LEAST-SQUARES STABILIZED FINITE ELEMENT COMPUTATIONS FOR ACOUSTICS

2006 ◽  
Vol 14 (01) ◽  
pp. 1-19 ◽  
Author(s):  
ISAAC HARARI ◽  
RADEK TEZAUR ◽  
CHARBEL FARHAT
Keyword(s):  
Least Squares ◽  
Discontinuous Galerkin ◽  
Large Scale ◽  
Dispersion Analysis ◽  
Stability Parameter ◽  
New Approach ◽  
One Dimensional ◽  
Stabilized Finite Element ◽  
Quadratic Interpolation ◽  
The Stability

One-dimensional analyses provide novel definitions of the Galerkin/least-squares stability parameter for quadratic interpolation. A new approach to the dispersion analysis of the Lagrange multiplier approximation in discontinuous Galerkin methods is presented. A series of computations comparing the performance of [Formula: see text] Galerkin and GLS methods with Q-8-2 DGM on large-scale problems shows superior DGM results on analogous meshes, both structured and unstructured. The degradation of the [Formula: see text] GLS stabilization on unstructured meshes may be a consequence of inadequate one-dimensional analysis used to derive the stability parameter.

DIAGRAMS FOR MAGNETOTELLURIC DATA

Geophysics ◽  
1976 ◽  
Vol 41 (4) ◽  
pp. 766-770 ◽  
Author(s):  
F. E. M. Lilley
Keyword(s):  
Impedance Tensor ◽  
Two Dimensional ◽  
Magnetotelluric Data ◽  
One Dimensional ◽  
Magnetic Components ◽  
Strike Direction ◽  
Electric And Magnetic Fields ◽  
The Relationship ◽  
Special Case ◽  
Phase Differences

Observed magnetotelluric data are often transformed to the frequency domain and expressed as the relationship [Formula: see text]where [Formula: see text] [Formula: see text] and [Formula: see text] [Formula: see text] represent electric and magnetic components measured along two orthogonal axes (in this paper, for simplicity, to be north and east, respectively). The elements [Formula: see text] comprise the magnetotelluric impedance tensor, and they are generally complex due to phase differences between the electric and magnetic fields. All quantities in equation (1) are frequency dependent. For the special case of “two‐dimensional” geology (where structure can be described as having a certain strike direction along which it does not vary), [Formula: see text] with [Formula: see text]. For the special case of “one‐dimensional” geology (where structure varies with depth only, as if horizontally layered), [Formula: see text] and [Formula: see text].

Direct inversion of one-dimensional magnetotelluric data

1983 ◽  
Vol 88 (B3) ◽  
pp. 2407 ◽  
Author(s):  
Shimon Coen ◽  
Franchesca Quercia ◽  
Maria Mackiewicz
Keyword(s):  
Magnetotelluric Data ◽  
One Dimensional ◽  
Direct Inversion
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