Integral equation modeling of three-dimensional magnetotelluric response

Conference · Sat Dec 01 00:00:00 EST 1979

OSTI ID:6718866

Ting, S C; Hohmann, G W

A three-dimensional (3D) volume integral equation was adapted to magnetotelluric (MT) modeling. Incorporating an integro-difference scheme increases the accuracy somewhat. Utilizing the two symmetry planes of a buried prismatic body and a normally incident plane wave source greatly reduces the required computation time and storage. Convergence checks and comparisons with one-dimensional (1D) and two-dimensional (2D) models indicate that the results are valid. Theoretical surface anomalies due to a 3D prismatic conductive body buried in a half-space earth are shown. Impedance tensor and magnetic transfer functions were obtained by imposing two different source polarizations. Manipulation of the impedance tensor and magnetic transfer functions yields the following MT quantities: apparent resistivity and phase, impedance polar diagrams, tipper direction and magnitude, principal directions, skew and ellipticity. With the preliminary analyses of these MT quantities, it was found that three-dimensionality is usually revealed by all of them. Two pairs of complementary parameters were recognized; apparent resistivity and phase, and skew and ellipticity. Because of surface charges at conductivity boundaries, low-frequency 3D responses are much different from 1D and 2D responses. Thus, in many cases, 3D models are required for interpreting MT data.

• Research Organization: Utah Univ., Salt Lake City (USA). Dept. of Geology and Geophysics
• DOE Contract Number: AC07-79ET27002
• OSTI ID: 6718866
• Report Number(s): DOE/ET/27002-4; CONF-7811181-1
• Conference Information: 48. annual international SEG meeting, San Francisco, CA, USA, 1 Nov 1978
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
DATA ANALYSIS
ELECTRICAL SURVEYS
ELECTROMAGNETIC SURVEYS
EQUATIONS
FUNCTIONS
GEOPHYSICAL SURVEYS
Geothermal Legacy
IMPEDANCE
INTEGRAL EQUATIONS
MAGNETOTELLURIC SURVEYS
MATHEMATICAL MODELS
SURVEYS
THREE-DIMENSIONAL CALCULATIONS
TRANSFER FUNCTIONS
TWO-DIMENSIONAL CALCULATIONS