3. EM/GPR Imaging Technologies
Effect of Survey Lines Oblique to the Strike Direction on Two-dimensional Inversion of Magnetotelluric Data
Tae Jong Lee, Myung Jin Nam and Yoonho Song
Korea Institute of Geoscience and Mineral Resources (KIGAM), Korea.
Abstract
A two-dimensional (2-D) magnetotelluric (MT) inversion assumes that 1) the subsurface structure is essentially 2-D, and that 2) the survey lines are perpendicular to the strike direction. In actual field survey, however, various factors prevent us from locating the survey line in right angle to the strike, such as lack of preliminary geological information, noise sources around, accessibility, and so on. In this study, we discuss how such an oblique angle between the survey line and the strike direction affects the 2-D inversion results. When the deviation angle is within 45 degree, 2-D inversion appeared to give reasonable estimation of 2-D structures. As the deviation angle getting larger, however, the 2-D inversion suffers from the convergence problem, especially in transverse electric (TE) mode. Inversion of transverse magnetic (TM) mode can converge even in case of large deviation angle, but the results cannot represent the subsurface model. Instead, three-dimensional (3-D) inversion of such line-surveyed data can give more reasonable result.
Last modified: Thu May 11 13:09:10 2006