Publication 155

The inability of magnetotelluric off-diagonal impedance tensor elements to sense oblique conductors in 3-D inversion

Kiyan, D., A.G. Jones, and J. Vozar


The advantages of modelling single profile magnetotelluric (MT) data with three- dimensional (3-D) inversion have previously been shown, both with a synthetic data set and field data set. In this paper, we use synthetic data sets from a North-South oriented prfile to demonstrate the importance of aligning the 3-D mesh and data coordinate system with the dominant geo-electrical strike direction in 3-D inverse modelling. The resistivity model investigated consists of a regional, 45 degrees east of north elongated 2-D conductive structure. We compare the results of full impedance tensor inversion with the results from inversion of only off-diagonal components of the MT impedance tensor. The 3-D inversion result obtained with the complete tensor elements yields the subsurface model closest to the original model, whereas the result of inverting only off-diagonal components is the poor imaging of the continuity of the conductive 2-D body. However, the conductor can be correctly recovered using only the off-diagonal components if the model mesh and the data are aligned with quasi-2-D geo-electrical strike.


Geophysical Journal International, 196, 1351–1364, doi:10.1093/gji/ggt470. [PDF]

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Alan G Jones / 14 February 2014 /