3. EM/GPR Imaging Technologies
Magnetotelluric Inversion using Reverse Time Migration Technique in Seismic Waveform Inversion
Taeyoung Ha(1) and Changsoo Shin(2)
(1) Department of Mathematical Sciences, Korea. (2) School of Civil, Urban and Geosystem Engineering, Korea.
Abstract
We propose a new algorithm for two dimensional magnetotelluric inversion. Our algorithm is MT inversion basing on the steepest descent method, borrowed from back-propagation technique of seismic inversion or reverse time migration, introduced in the middle 1980's by Lailly and Tarantola. The steepest descent direction can be calculated efficiently by using the symmetry of numerical Green's function derived from a mixed finite element method proposed by Nedelec for Maxwell's equation,without calculating Jacobian matrix directly. As introduced in the recent waveform inversion algorithm by Shin and Min, we build three different objective functions by taking a logarithm of complex apparent resistivity. These objective functions can be naturally separated into amplitude inversion, phase inversion and simultaneous inversion. We demonstrate our algorithm by showing two inversion results for synthetic data. The numerical procedure is shown as the synthetic data, and we calibrate our algorithm.
Last modified: Wed May 10 08:28:50 2006