INVESTIGATION OF LARGE SCALE INHOMOGENEITIES IN THE EARTH BY MAGNETOTELLURIC METHOD
Abstract
IN THE MAGNETOTELLURIC ANALYSIS PROPOSED BY Cagniard, a resistivity profile of a homogeneous stratified earth model is determined from the ratio of the tangential components of the natural electric and magnetic fields at the surface of th earth. This type of analysis is often confused by the fact that apparent resistivity estimates obtained from data recorded at one site on different occasions may vary considerably. Also the apparent resistivities computed from one component of the E field and its orthogonal H field component may be significantly different from those computed from another pair of orthogonal field components. Cantwell points out that these variations may, at least in part, be due to two dimensional in omoge iti s a /or iso ropies toget er with randomly polarized magnetotelluric fields. Accordingly, he has suggested tes ing the wave impedance of the earth as a rank two ten or. This report de crib s a measurement and analysis procedure developed using a model based on a two dimensional wave impedance tensor. A rotation of the measuring axis to minimize the mai diagonal terms in the impedance tensor yields a reasonably con istent stimate of the direction and magnitude of a major inhomogeneity in th apparent resistivity profile. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1962
- Accession Number
- AD0277428
Entities
People
- F.x. Jr. Bostick
- H.w. Smith
Organizations
- University of Texas at Austin