摘要：A conventional magnetotelluric (MT) survey layout implies measurements of horizontal electric and magnetic fields at every site with subsequent estimation and interpretation of impedance tensors ({Z}) or dependent responses, such as apparent resistivities and phases. In this work, we assess advantages and disadvantages of complementing or substituting conventional MT with inter-site transfer functions such as inter-site impedance tensor, ({Q}) , horizontal magnetic, ({M}) , and horizontal electric, ({T}) , tensors. Our analysis is based on a 3-D inversion of synthetic responses calculated for a 3-D model which consists of two buried adjacent (resistive and conductive) blocks and thin resistor above them. The (regularized) 3-D inversion is performed using scalable 3-D MT inverse solver with forward modelling engine based on a contracting integral equation approach. The inversion exploits gradient-type (quasi-Newton) optimization algorithm and invokes adjoint sources approach to compute misfits’ gradients. From our model study, we conclude that: (1) 3-D inversion of either ({Z}) or ({Q}) tensors recovers the “true” structures equally well. This, in particular, raises the question whether we need magnetic field measurements at every survey site in the course of 3-D MT studies; (2) recovery of true structures is slightly worse if ({T}) tensor is inverted, and significantly worse if ({M}) tensor is inverted; (3) simultaneous inversion of ({Z}) and ({M}) (or ({Z}) and ({T}) ) does not improve the recovery of true structures compared to individual inversion of ({Z}) or ({Q}) ; (4) location of reference site, which is required for calculating inter-site ({Q}) , ({T}) and ({M}) tensors, has also marginal effect on the inversion results.
