Static distortion of magnetotelluric data is a common effect that can
impede the reliable imaging of subsurface structures. Recently we
presented an inversion approach that includes a mathematical description
of the effect of static distortion as inversion parameters and
demonstrated its efficiency with real data. We now systematically
investigate the stability of this inversion approach with respect to
different inversion strategies, starting models and model
parametrizations. We utilize a dataset of 310 magnetotelluric sites that
has been acquired for geothermal exploration. In addition, to impedance
tensor estimates over a broad frequency range, the dataset also
comprises transient electromagnetic measurements to determine near
surface conductivity and estimates of distortion at each site. We
therefore can compare our inversion approach to these distortion
estimates and the resulting inversion models. Our experiments show that
inversion with distortion correction produces stable results for various
different inversion strategies and for different starting models.
Compared to inversion without distortion correction, we can reproduce
the observed data better and reduce subsurface artefacts. In contrast,
shifting the impedance curves at high frequencies to match the transient
electromagnetic measurements reduces the misfit of the starting model,
but does not have a strong impact on the final results. Thus our results
suggest that including a description of distortion in the inversion is
more efficient and should become a standard approach for magnetotelluric
inversion.