# Interpretation of 1D Vector Controlled-Source Audio-Magnetotelluric (CSAMT) Data Using Full Solution Modeling

## DOI:

https://doi.org/10.5614/j.math.fund.sci.2013.45.2.7## Keywords:

1D Occam inversion, controlled-source audio-magnetotellurics, full solution 1D CSAMT forward modeling, scalar CSAMT, vector CSAMT interpretation.## Abstract

In conventional controlled-source audio-magnetotelluric (CSAMT) prospecting, scalar CSAMT measurement is usually performed because of its simplicity and low operational cost. Since the structure of earthâ€™s conductivity is complex, the scalar CSAMT method can lead to a less accurate interpretation. The complex conditions need more sophisticated measurements, such as vector or tensor CSAMT, to interpret the data. This paper presents 1D vector CSAMT interpretation. A full solution 1D CSAMT forward modeling has been developed and used to interpret both vector and scalar CSAMT data. Occamâ€™s smoothness constrained inversion was used to test the vector and scalar CSAMT interpretations. The results indicate the importance of vector CSAMT to interpret CSAMT data in complex geological system.## References

Goldstein, M.A., & Strangway, D.W., Audio-Frequency Magnetotellurics with A Grounded Electric Dipole Source, Geophysics, 40, pp. 669-683, 1975.

Unsworth, M.J., Travis, B.J., & Chave, A.D., Electromagnetic Induction by a Finite Electric Dipole Source Over a 2D Earth, Geophysics, 58, pp. 198-214, 1993.

Mitsuhata, Y., 2-D Electromagnetic Modeling by Finite-Element Method with a Dipole Source and Topography, Geophysics, 65, pp. 465-475, 2000.

Li, Y., & Key, K., 2D Marine Controlled-Source Electromagnetic Modeling: Part 1 " An Adaptive Finite-Element Algorithm, Geophysics, 72, pp. WA51-WA62, 2007.

Streich, R., 3D Finite Difference Frequency Modeling of Controlled Source Electromagnetic Data: Direct Solution and Optimization for High Accuracy, Geophysics 74, pp. 95-105, 2009.

Sasaki, Y., Yoshihiro, Y., & Matsuo, K., Resistivity Imaging of Controlled-Source Audiofrequency Magnetotelluric Data, Geophysics, 57, pp. 952-955, 1992.

Yamashita M., Hallof, P.G., & Pelton, W.H., CSAMT Case History with a Multichannel CSAMT System and Near Field Data Correction, 55th SEG Annual Convention, pp. 276-278, 1985.

Bartel, L.C., & Jacobson, R.D., Results of a Controlled Source Audiofrequency Magnetotelluric Survey at the Puhimau Thermal Area, Kilauea Volcano, Hawaii, Geophysics, 52, pp. 665-677, 1987.

Routh, S.P., & Oldenburg, D.W., Inversion of Controlled Source Audio Frequency Magnetotelluric Data for a Horizontally Layered Earth, Geophysics, 64, pp. 1689-1697, 1999.

Zonge, K.L., & Hughes, L.J., Controlled Source Audiofrequency Magnetotellurics, in: Nabighian, M.N. (ed.), Electromagnetic Electromagnetic Methods in Applied Geophysics: Volume 2, Application, Society of Exploration Geophysicist, Tulsa, Oklahoma, 1991.

Constable, S.C., Parker R.L, & deGroot, C., Occam's Inversion: A Practical Algorithm for Generating Smooth Models from EM Sounding Data, Geophysics, 52, pp. 289-300, 1987.

Kaufman, A.A., & Keller G.V., Frequency and Transient Sounding, Elsevier, Amsterdam, 1983.

Ward, S.H., & Hohmann, G.W., EM Theory for Geophysical Applications, in Nabighian, M.N. (ed.), Electromagnetic Methods in Applied Geophysics, Vol. 1: Theory, Society of Exploration Geophysicist, Tulsa, Oklahoma, 1988.

Singh, N.P., & Mogi, T., EMDPLER: A F77 Program for Modeling the EM Response of Dipolar Sources over the Non-Magnetic Layer Earth Model, Computer and Geosciences 36, pp. 430-440, 2010.

Cagniard, L., Basic Theory of the Magneto-Telluric Method of Geophysical Prospecting, Geophysics, 18, pp. 605-635, 1953.

Anderson W.L., Numerical Integration of Related Hankel Transform of Order 0 and 1 by Adaptive Digital Filtering, Geophysics 44, pp. 1287-1305, 1979.

Anderson, W.L., A Hybrid Fast Hankel Transforms Algorithm for EM Modeling, Geophysics, 54, pp. 263-266, 1989.

Srigutomo, W., Kagiyama, T., Kanda, W., & Utada, H., Study of Deep Sounding Time Domain EM (TDEM) Method using Horizontal Electric Dipole to infer Subsurface Resistivity Structure. Indonesian Journal of Physics, 16, pp. 115-125, 2005.

Aster, R.P., Borchers, B., & Thurber, C.H., Parameters Estimation and Inverse Problems, Elsevier Academic Press, Oxford, U.K., 2005.